Magnetic recording medium, recording/reproducing apparatus, and stamper

ABSTRACT

On a magnetic recording medium, M sets of burst patterns are formed along a direction of rotation of a substrate in each burst pattern region, where M is a natural number of two or higher. Each burst pattern is formed so as to include two types of burst signal units that are positioned at different distances from a center of data track patterns and have an equal length along a radial direction of the substrate. The length along the radial direction is (2·M/N) times the track pitch, where N is a natural number of two or higher. In a predetermined range where both ends in the radial direction do not match a center in the radial direction of a burst pattern, (2·M) centers in the radial direction of the burst patterns are present at intervals of (1/N) times the track pitch in the radial direction, the two types of burst signal units are formed of non-recording regions and do not overlap each other in the direction of rotation, centers of the burst signal units in the radial direction are separated by (M/N) times the track pitch, and facing end parts in the radial direction of the burst signal units are separated via recording regions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic recording medium on whichburst patterns are formed by patterns that include recording regions andnon-recording regions, a recording/reproducing apparatus equipped withthe magnetic recording medium, and a stamper for manufacturing themagnetic recording medium.

2. Description of the Related Art

As examples of this type of magnetic recording medium andrecording/reproducing apparatus, Japanese Laid-Open Patent PublicationNo. H06-111502 discloses a magnetic disk apparatus equipped with amagnetic disk on which recording track patterns and servo patterns areformed by concave/convex patterns. On the magnetic disk provided in themagnetic disk apparatus, the recording track patterns and the servopatterns are formed by concave/convex patterns formed in a magneticlayer on a disk substrate. More specifically, as shown in FIG. 22, on aconventional magnetic disk (hereinafter referred to as a “magnetic disk10 x 1”), a plurality of track patterns Pw formed in belt-like shapesalong the direction of rotation of the magnetic disk 10 x 1 (thedirection of the arrow R shown in FIG. 22) and servo patterns Ps1, Ps2formed in servo pattern regions are formed by the concave/convexpatterns described above. Note that on the magnetic disk 10 x 1 shown inFIG. 22 and a magnetic disk 10 x 2 shown in FIG. 23 described later,formation regions of convex parts (recording regions) in theconcave/convex patterns are shown by obliquely shaded areas andformation regions of concave parts (non-recording regions) in theconcave/convex patterns are shown by the non-shaded (i.e., white)regions.

The servo patterns Ps1, Ps2, . . . are servo patterns used to detect theposition of a magnetic head and thereby make the magnetic head on-trackto a desired track pattern Pw. The servo patterns Ps1, Ps2 are formed asa pair to function as a burst pattern. Also, on the magnetic disk 10 x1, the widths Ts of the servo patterns Ps1, Ps2 are equal to theformation pitch of the track patterns Pw (referred to as the “trackpitch Tp”) and both ends in the radial direction of the servo patternsPs1, Ps2 are positioned so as to match the centers of the track patternsPw (the positions shown by broken lines in FIG. 22: centers of thetracks). The formation positions of the servo patterns Ps1, Ps2 differby the track pitch Tp in the radial direction of the magnetic disk 10 x1 and are separated from one another in the direction of rotation.

On the other hand, another magnetic disk (hereinafter referred to as“magnetic disk 10 x 2”) on which four types of pattern, servo patternsPs1 to Ps4, are formed as shown in FIG. 23 is disclosed in the samepublication. On the magnetic disk 10 x 2, the servo patterns Ps1, Ps2form a pair and function as a set of burst patterns and the servopatterns Ps3, Ps4 form a pair and function as another set of burstpatterns. Also, on the magnetic disk 10 x 2, the widths Ts of the servopatterns Ps1 to Ps4 are formed so as to be double the track pitch Tp. Inaddition, on the magnetic disk 10 x 2, both ends in the radial directionof the servo patterns Ps1, Ps2 are formed so as to match the centers(the positions shown by broken lines in FIG. 23: centers of the tracks)of track patterns Pw and both ends in the radial direction of the servopatterns Ps3, Ps4 are formed so as to match the centers of other trackpatterns Pw. The formation positions of the servo patterns Ps1, Ps2differ by double the track pitch Tp in the radial direction of themagnetic disk 10 x 2 and are separated from one another in the directionof rotation. The formation positions of the servo patterns Ps3, Ps4 alsodiffer by double the track pitch Tp in the radial direction and areseparated from one another in the direction of rotation. In addition,the servo patterns Ps1 to Ps4 are formed so that the center in theradial direction of a burst pattern composed of the servo patterns Ps1,Ps2 and the center in the radial direction of a burst pattern composedof the servo patterns Ps3, Ps4 differ by the track pitch Tp in theradial direction.

SUMMARY OF THE INVENTION

However, by investigating the conventional magnetic disks 10 x 1, 10 x2, the present inventors discovered the following problem. That is, tomake present-day magnetic disks capable of high-density recording, it isnecessary to increase the track density of data recording tracks, andtherefore tracking servo control needs to be carried out with higherprecision. More specifically, it is necessary to avoid (suppress) theproduction of zones (zones with a width in the radial direction:hereinafter “dead zones”) for which it is difficult to detect theposition of a magnetic head using a PES (Position Error Signal) based onan output signal outputted from the magnetic head corresponding to aburst pattern when the burst pattern passes below the magnetic head, andthe demands being placed on the width (a length in the radial direction:hereinafter “detectable zone”) in which the position of the magnetichead can be detected using the PES are becoming increasingly severe asthe recording density increases. In a state where the output signaloutputted from the magnetic head varies due to the effects of noise andthe like, for example, the detectable zone described above can becomeeven narrower. When this happens, the detectable zone becomes evennarrower on magnetic recording media including the conventional magneticdisks 10 x 1, 10 x 2, resulting in the risk of dead zones beingproduced. For this reason, as the recording density increases, there isthe risk of it becoming difficult to carry out proper tracking servocontrol for this type of magnetic recording media.

Also, on the conventional magnetic disk 10 x 1, since there is only oneset of burst patterns composed of the servo patterns Ps1, Ps2, it isnecessary to specify a position of the magnetic head along the radialdirection based on the PES when a single set of burst patterns passesbelow the magnetic head. However, as shown in FIG. 22, on theconventional magnetic disk 10 x 1, since the width Ts of the servopatterns Ps1 and Ps2 is equal to the track pitch Tp, if the width Wr1 xof a reproducing element Rx of the magnetic head is narrower than thetrack pitch Tp, the signal level of the output signal from the magnetichead will have the same level when an inner periphery side of the servopattern Ps1 passes below the reproducing element Rx (when thereproducing element Rx passes above a position P11 on the magnetic disk10 x 1) and when an outer periphery side of the servo pattern Ps1 passesbelow the reproducing element Rx (when the reproducing element Rx passesabove a position P12 on the magnetic disk 10 x 1), for example. Thismeans dead zones for detecting the position of the magnetic head areproduced, and therefore it is difficult to specify over which of thepositions P11 and P12 the reproducing element Rx is positioned based onthe PES.

Similarly, if the width Wr2 x of the reproducing element Rx of themagnetic head is wider than the track pitch Tp (the width Ts), thesignal level of the output signal from the magnetic head will have thesame level when the servo pattern Ps1 passes below the inner peripheryside of the reproducing element Rx (when the reproducing element Rxpasses above a position P13 on the magnetic disk 10 x 1), and when theservo pattern Ps1 passes below the outer periphery side of thereproducing element Rx (when the reproducing element Rx passes above aposition P14 on the magnetic disk 10 x 1), for example. As a result, inthis case also, dead zones are produced, so that it is difficult tospecify over which of the positions P13 and P14 the reproducing elementRx is positioned based on the PES. Accordingly, since it is necessary toset the track pitch Tp and the width Ts so that the track pitch Tp(which is equal to the width Ts of the servo patterns Ps1, Ps2) and thelength in the radial direction of the reproducing element Rx of themagnetic head match, there has been the problem of limited freedom fordesigning the data track patterns and servo patterns on the conventionalmagnetic disk 10 x 1 (i.e., limited freedom for the selection of patternsizes).

On the other hand, the conventional magnetic disk 10 x 2 has two sets ofburst patterns composed of the servo patterns Ps1 to Ps4, with thewidths Ts of the servo patterns Ps1 to Ps4 being sufficiently wider thanthe track pitch Tp. This means that with the conventional magnetic disk10 x 2, if the reproducing head width (the width of the reproducingelement Rx) is wider than the track pitch Tp, it will be possible tospecify a position along the radial direction of the magnetic head (thereproducing element Rx) based on the PES when either of the burstpattern composed of the servo patterns Ps1, Ps2 and the burst patterncomposed of the servo patterns Ps3, Ps4 passes below the reproducingelement Rx. This means that there is greater freedom for selecting apattern size with the conventional magnetic disk 10 x 2 than with themagnetic disk 10 x 1.

However, on the conventional magnetic disk 10 x 2, as shown in FIG. 23,if the width Wr3 x of the reproducing element Rx is narrower than thetrack pitch Tp (that is, narrower than half the width Ts of the servopatterns Ps1, Ps2), the signal level of the output signal from themagnetic head will have the same level when the inner periphery side ofthe servo pattern Ps3 passes below the reproducing element Rx after acenter-right part of the servo pattern Ps1 has passed below thereproducing element Rx (i.e., when the reproducing element Rx passes inorder above the positions P15, P17 on the magnetic disk 10 x 2) and whena center-left part of the servo pattern Ps3 passes below the reproducingelement Rx after the outer periphery side of the servo pattern Ps1 haspassed below the reproducing element Rx (i.e., when the reproducingelement Rx passes in order above the positions P16, P18 on the magneticdisk 10 x 2). As a result, since dead zones are produced when thereproducing head width is narrower than the track pitch Tp, it willstill be difficult to specify over which of the positions P15, P17 andP16, P18 the reproducing element Rx is positioned based on the PES.Accordingly, on the conventional magnetic disk 10 x 2, the track pitchTp needs to be made narrower than the reproducing head width. This meansthat with the conventional magnetic disk 10 x 2, since a reproducingelement Rx where the reproducing head width is greater than the trackpitch Tp is used, there is the risk of a “side reading” phenomenonoccurring where a magnetic signal is read from an adjacent track. Inthis way, with the conventional magnetic disk 10 x 2, there is theproblem that it is difficult to increase the freedom with which thepattern size can be selected while avoiding the occurrence of sidereading.

The present invention was conceived in view of the problems describedabove and it is a principal object of the present invention to provide amagnetic recording medium and a recording/reproducing apparatus thatenable servo patterns and the like to be designed with greater freedom,can avoid side reading, and can also sufficiently widen a detectablezone, and to also provide a stamper that can easily manufacture suchmagnetic recording medium.

To achieve the stated object, on a magnetic recording medium accordingto the present invention are formed: servo patterns formed in servopattern regions on at least one surface of a substrate by patternsincluding recording regions and non-recording regions; and data trackpatterns where a plurality of data recording tracks are formed with apredetermined track pitch in data recording regions on the at least onesurface, wherein M sets of burst patterns are formed along a directionof rotation of the substrate in a burst pattern region in each servopattern region, where M is a natural number of two or higher, each burstpattern is formed so as to include two types of burst signal units thatare positioned at different distances from a center of the data trackpatterns and have an equal length along a radial direction of thesubstrate, the length along the radial direction being (2·M/N) times thetrack pitch, where N is a natural number of two or higher, and so thatin a predetermined range where both ends in the radial direction do notmatch a center in the radial direction of a burst pattern, (2·M) centersin the radial direction of the burst patterns are present at intervalsof (1/N) times the track pitch in the radial direction, and the twotypes of burst signal units are constructed by the non-recording regionsso that a first type of burst signal units and a second type of burstsignal units out of the two types of burst signal units do not overlapin the direction of rotation, centers in the radial direction of theburst signal units of a same type are separated in the radial directionby (2·M/N) times the track pitch, centers in the radial direction of thefirst type of burst signal units and centers in the radial direction ofthe second type of burst signal units are separated in the radialdirection by (M/N) times the track pitch, and in at least one part outof regions from an inner periphery region to an outer periphery regionof the substrate, end parts positioned close to the second type of burstsignal units out of both end parts in the radial direction of the firsttype of burst signal units and end parts positioned close to the firsttype of burst signal units out of both end parts in the radial directionof the second type of burst signal units are separated in the radialdirection via the recording regions. Note that the expression “recordingregion” in the present specification refers to a region constructed soas to be able to store a recorded magnetic signal in a readable manner(that is, a region with an ability to store a magnetic signal in areadable manner). Also, the expression “non-recording region” in thepresent specification refers to a region constructed so that the abilityto store a recorded magnetic signal in a readable manner is lower thanthe ability of a recording region or to a region that effectively has nosuch ability. More specifically, a “non-recording region” for thepresent specification refers to a region from which a smaller magneticfield is produced in a state where a magnetic signal has been recordedthan the magnetic field produced from a recording region or to a regionfrom which a magnetic field is effectively not produced. In addition, inthe present specification, a “value produced by multiplying two by M” iswritten as “2·M” and a “value produced by dividing one by N” is writtenas “1/N”.

According to the above magnetic recording medium, by forming M sets ofburst patterns, which include two types of burst signal unitsconstructed of non-recording regions, along the direction of rotation ofa substrate and forming the burst signal units so that in at least onepart out of regions from an inner periphery region to an outer peripheryregion of the substrate, end parts positioned close to the second typeof burst signal units out of both end parts in the radial direction ofthe first type of burst signal units and end parts positioned close tothe first type of burst signal units out of both end parts in the radialdirection of the second type of burst signal units are separated in theradial direction via recording regions, it is possible to sufficientlywiden the detectable zone for detecting the position of the magnetichead based on the PES, and as a result, even if the output signaloutputted from the magnetic head corresponding to a burst pattern variesdue to noise or the like, it will still be possible to reliably detect apositional displacement of the magnetic head and to carry out propertracking servo control. Also, unlike the conventional magnetic disk 10 x1 where there is only one set of burst patterns, there is no need forthe width of the reproducing element of the magnetic head to match thetrack pitch, and therefore the data track patterns and the servopatterns can be designed with increased freedom. Also, unlike theconventional magnetic disk 10 x 2, the width of the reproducing elementdoes not need to be wider than the track pitch, and therefore it ispossible to sufficiently suppress “side reading”.

On another magnetic recording medium according to the present inventionare formed: servo patterns formed in servo pattern regions on at leastone surface of a substrate by patterns including recording regions andnon-recording regions; and data track patterns where a plurality of datarecording tracks are formed with a predetermined track pitch in datarecording regions on the at least one surface, wherein M sets of burstpatterns are formed in a direction of rotation of the substrate in aburst pattern region in each servo pattern region, where M is a naturalnumber of two or higher, each burst pattern is formed so as to includetwo types of burst signal units that are positioned at differentdistances from a center of the data track patterns and have an equallength along a radial direction of the substrate, the length along theradial direction being (2·M/N) times the track pitch, where N is anatural number of two or higher, and so that in a predetermined rangewhere both ends in the radial direction do not match a center in theradial direction of a burst pattern, (2·M) centers in the radialdirection of the burst patterns are present at intervals of (1/N) timesthe track pitch in the radial direction, and the two types of burstsignal units are constructed by the recording regions so that a firsttype of burst signal units and a second type of burst signal units outof the two types of burst signal units do not overlap in the directionof rotation, centers in the radial direction of the burst signal unitsof a same type are separated in the radial direction by (2·M/N) timesthe track pitch, centers in the radial direction of the first type ofburst signal units and centers in the radial direction of the secondtype of burst signal units are separated in the radial direction by(M/N) times the track pitch, and in at least one part out of regionsfrom an inner periphery region to an outer periphery region of thesubstrate, end regions including end parts positioned close to thesecond type of burst signal units out of both end parts in the radialdirection of the first type of burst signal units and end regionsincluding end parts positioned close to the first type of burst signalunits out of both end parts in the radial direction of the second typeof burst signal units overlap in the radial direction.

According to the above magnetic recording medium, by forming M sets ofburst patterns, which include two types of burst signal unitsconstructed of recording regions, along the direction of rotation of asubstrate and forming the burst signal units so that in at least onepart out of regions from an inner periphery region to an outer peripheryregion of the substrate, end regions including end parts positionedclose to the second type of burst signal units out of both end parts inthe radial direction of the first type of burst signal units and endregions including end parts positioned close to the first type of burstsignal units out of both end parts in the radial direction of the secondtype of burst signal units overlap in the radial direction, it ispossible to sufficiently widen the detectable zone for detecting theposition of the magnetic head based on the PES, and as a result, even ifthe output signal outputted from the magnetic head corresponding to aburst pattern varies due to noise or the like, it will still be possibleto reliably detect a positional displacement of the magnetic head and tocarry out proper tracking servo control. Also, unlike the conventionalmagnetic disk 10 x 1 where there is only one set of burst patterns,there is no need for the width of the reproducing element of themagnetic head to match the track pitch, and therefore the data trackpatterns and the servo patterns can be designed with increased freedom.Also, unlike the conventional magnetic disk 10 x 2, the width of thereproducing element does not need to be wider than the track pitch, andtherefore it is possible to sufficiently suppress “side reading”.

Also, a recording/reproducing apparatus according to the presentinvention includes: the magnetic recording medium described above wherethe burst signal units are constructed of non-recording regions; amagnetic head that reads a control signal used for tracking servocontrol from the servo pattern regions of the magnetic recording medium;and a control unit that carries out the tracking servo control based onthe control signal read via the magnetic head, wherein the burstpatterns are formed on the magnetic recording medium so as to satisfy acondition “(M+1)·Tp/N−BW≦Wr≦(M−1)·Tp/N+BW” where Wr is a reproducinghead width of the magnetic head, BW is a length along the radialdirection of the burst signal units, and Tp is the track pitch. Notethat the expression “reproducing head width of the magnetic head” in thepresent specification refers to a length in the width direction (thedirection corresponding to the radial direction of the magneticrecording medium) of a surface of a reproducing element (an MR elementor the like) of a magnetic head that faces the magnetic recordingmedium.

According to the above recording/reproducing apparatus, by forming theburst patterns of the magnetic recording medium so as to satisfy thecondition “(M+1)·Tp/N−BW≦Wr≦(M−1)·Tp/N+BW”, it is possible tosufficiently widen the detectable zone for detecting the position of themagnetic head based on the PES by using a magnetic head with areproducing element with a width (Wr) that satisfies the above conditionwithout producing dead zones for the burst patterns, which makes itpossible to carry out proper tracking servo control. Here, unlike theconventional magnetic disk 10 x 1, since the track pitch and the lengthalong the radial direction of the burst signal units are not primarilydetermined by the width of the reproducing element, the data trackpatterns and the servo patterns can be designed with increased freedom.This means that the track pitch and the length along the radialdirection of the burst signal units can be suitably changed inaccordance with objects such as increasing the track density andavoiding side reading. Also, unlike the conventional magnetic disk 10 x2, the width of the reproducing element does not need to be made widerthan the track pitch, and therefore side reading can be sufficientlyavoided. By doing so, it is possible to provide a recording/reproducingapparatus equipped with a magnetic recording medium capable ofhigh-density recording and not susceptible to reproducing errors.

Another recording/reproducing apparatus according to the presentinvention includes: the magnetic recording medium described above wherethe burst signal units are constructed of the recording regions; amagnetic head that reads a control signal used for tracking servocontrol from the servo pattern regions of the magnetic recording medium;and a control unit that carries out the tracking servo control based onthe control signal read via the magnetic head, wherein the burstpatterns are formed on the magnetic recording medium so as to satisfy acondition “(1−M)·Tp/N+BW≦Wr≦(3·M−1)·Tp/N−BW” where Wr is a reproducinghead width of the magnetic head, BW is a length along the radialdirection of the burst signal units, and Tp is the track pitch.

According to the above recording/reproducing apparatus, by forming theburst patterns of the magnetic recording medium so as to satisfy thecondition “(1−M)·Tp/N+BW≦Wr≦(3·M−1)·Tp/N−BW”, it is possible tosufficiently widen the detectable zone for detecting the position of themagnetic head based on the PES by using a magnetic head with areproducing element with a width (Wr) that satisfies the above conditionwithout producing dead zones for the burst patterns, which makes itpossible to carry out proper tracking servo control. Here, unlike theconventional magnetic disk 10 x 1, since the track pitch and the lengthalong the radial direction of the burst signal units are not primarilydetermined by the width of the reproducing element, the data trackpatterns and the servo patterns can be designed with increased freedom.This means that the track pitch and the length along the radialdirection of the burst signal units can be suitably changed inaccordance with objects such as increasing the track density andavoiding side reading. Also, unlike the conventional magnetic disk 10 x2, the width of the reproducing element does not need to be made widerthan the track pitch, and therefore side reading can be sufficientlyavoided. By doing so, it is possible to provide a recording/reproducingapparatus equipped with a magnetic recording medium capable ofhigh-density recording and not susceptible to reproducing errors.

A stamper according to the present invention has a concave/convexpattern including convex parts formed corresponding to one region out ofthe recording regions and the non-recording regions of the patterns onthe magnetic recording medium described above where the burst signalunits are constructed of the non-recording regions and concave partsformed corresponding to other regions in the patterns on the magneticrecording medium.

According to the above stamper according to the present invention, byhaving a concave/convex pattern including convex parts formedcorresponding to one region out of the recording regions and thenon-recording regions of the patterns on the magnetic recording mediumdescribed above where the burst signal units are constructed ofnon-recording regions and concave parts formed corresponding to otherregions in the patterns on the magnetic recording medium, it is possibleto easily manufacture, using a method such as imprinting, a magneticrecording medium with burst patterns where the detectable zone fordetecting the position of the magnetic head based on the PES issufficiently wide.

Another stamper according to the present invention has a concave/convexpattern including convex parts formed corresponding to one region out ofthe recording regions and the non-recording regions of the patterns onthe magnetic recording medium described above where the burst signalunits are constructed of the recording regions and concave parts formedcorresponding to other regions in the patterns on the magnetic recordingmedium.

According to the above stamper, by having a concave/convex patternincluding convex parts formed corresponding to one region out of therecording regions and the non-recording regions of the patterns on themagnetic recording medium described above where the burst signal unitsare constructed of recording regions and concave parts formedcorresponding to other regions in the patterns on the magnetic recordingmedium, it is possible to easily manufacture, using a method such asimprinting, a magnetic recording medium with burst patterns where thedetectable zone for detecting the position of the magnetic head based onthe PES is sufficiently wide.

It should be noted that the disclosure of the present invention relatesto a content of Japanese Patent Application 2005-039154 that was filedon 16 Feb. 2005 and the entire content of which is herein incorporatedby reference.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will beexplained in more detail below with reference to the attached drawings,wherein:

FIG. 1 is a diagram showing the construction of a hard disk drive;

FIG. 2 is a cross-sectional view showing the layer construction of themagnetic disk shown in FIG. 1;

FIG. 3 is a plan view of the magnetic disk;

FIG. 4 is a plan view of the magnetic disk showing examples of variouspatterns formed in a servo pattern region;

FIG. 5 is a plan view of the magnetic disk showing examples of burstpatterns formed in a first burst region to fourth burst region in theburst pattern region;

FIG. 6 is a cross-sectional view showing the layer construction of apreform;

FIG. 7 is a cross-sectional view of a stamper;

FIG. 8 is a cross-sectional view of a state where a concave/convexpattern of a stamper has been pressed into a resin layer of the preform;

FIG. 9 is a cross-sectional view of a state where a concave/convexpattern (a resin mask) has been formed on a mask layer by separating astamper from the resin layer in the state shown in FIG. 8;

FIG. 10 is a cross-sectional view of a state where a concave/convexpattern (mask) has been formed on a magnetic layer by etching the masklayer with the concave/convex pattern as a mask;

FIG. 11 is a cross-sectional view of a state where a concave/convexpattern has been formed on an intermediate layer by etching the magneticlayer with the concave/convex pattern as a mask;

FIG. 12 is a cross-sectional view of the preform in a state where alayer of non-magnetic material has been formed so as to cover theconcave/convex pattern;

FIG. 13 is a cross-sectional view of a state where the surface of thenon-magnetic material has been etched to become flat;

FIG. 14 is a diagram useful in explaining the relationship between (i)positions (movement amounts) of a reproducing element on the magneticdisk and (ii) an output level of an output signal from a magnetic headand a PES;

FIG. 15 is a diagram useful in explaining the relationship between theservo patterns on the magnetic disk and the width of the reproducingelement;

FIG. 16 is a plan view of a magnetic disk showing examples of variouspatterns formed in a servo pattern region;

FIG. 17 is a plan view of a magnetic disk showing one example of theburst patterns formed in a first burst region to a fourth burst regionin a burst pattern region;

FIG. 18 is a diagram useful in explaining the relationship between (i)positions (movement amounts) of a reproducing element on the magneticdisk and (ii) an output level of an output signal from a magnetic headand a PES;

FIG. 19 is a diagram useful in explaining the relationship between theservo patterns on the magnetic disk and the width of the reproducingelement;

FIG. 20 is a cross-sectional view showing the layer construction of amagnetic disk;

FIG. 21 is a cross-sectional view showing the layer construction of amagnetic disk;

FIG. 22 is a plan view of a conventional magnetic disk showing oneexample of burst patterns; and

FIG. 23 is a plan view of another conventional magnetic disk showing oneexample of burst patterns.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of a magnetic recording medium and arecording/reproducing apparatus according to the present invention willnow be described with reference to the attached drawings.

The hard disk drive 1 shown in FIG. 1 is one example of arecording/reproducing apparatus according to the present invention,includes a motor 2, a magnetic head 3, a detection unit 4, a driver 5, acontrol unit 6, a storage unit 7, and a magnetic disk 10A, and iscapable of recording and reproducing various kinds of data. The motor 2rotates the magnetic disk 10A at a fixed rotational speed, such as 4200rpm, under the control of the control unit 6. The magnetic head 3 isattached to an actuator 3 b via a swing arm 3 a and is moved above themagnetic disk 10A during the recording and reproducing of recording dataon the magnetic disk 10A by the actuator 3 b. Also, the magnetic head 3carries out reads of servo data from servo pattern regions Asa (see FIG.4) of the magnetic disk 10A, magnetic writes of recording data in datarecording regions At (see FIG. 4), and reads of recording data that hasbeen magnetically written in the data recording regions At. It should benoted that although the magnetic head 3 is actually constructed byforming a reproducing element Ra (see FIG. 5) and a recording element(not shown) on a base surface (air bearing surface) of a slider thatcauses the magnetic head 3 to fly above the magnetic disk 10A, theslider and the recording element have been omitted from thisspecification and the drawings. Here, the width Wr in the widthdirection (a direction corresponding to the radial direction of themagnetic disk 10A) of a surface of the reproducing element Ra that facesthe magnetic disk 10A is set so as to satisfy a predetermined conditiondescribed later. The actuator 3 b swings the swing arm 3 a by a drivingcurrent supplied from the driver 5 under the control of the control unit6 and thereby moves the magnetic head 3 to an arbitraryrecording/reproducing position (an arbitrary track) above the magneticdisk 10A.

The detection unit 4 obtains (detects) servo data from the output signaloutputted from the magnetic head 3 and outputs the servo data to thecontrol unit 6. The driver 5 controls the actuator 3 b in accordancewith a control signal outputted from the control unit 6 so that themagnetic head 3 is made on-track to a desired track. The control unit 6carries out overall control of the hard disk drive 1. The control unit 6is one example of a “control unit” for the present invention, andcontrols the driver 5 based on a burst signal out of the servo data (oneexample of a “control signal read via the magnetic head”) outputted fromthe detection unit 4 (i.e., the control unit 6 executes a tracking servocontrol process). The storage unit 7 stores an operation program of thecontrol unit 6 and the like.

On the other hand, the magnetic disk 10A is one example of a “magneticrecording medium” for the present invention and is disposed togetherwith the above-described motor 2, the magnetic head 3, and the likeinside a housing of the hard disk drive 1. The magnetic disk 10A is adiscrete track-type magnetic disk (patterned medium) on which recordingdata can be recorded by a perpendicular recording method, and as shownin FIG. 2 is constructed so that a soft magnetic layer 12, anintermediate layer 13, and a magnetic layer 14 are formed in thementioned order on a glass substrate 11. Here, the magnetic layer 14constructs concave/convex patterns 40 constructed of convex parts 40 a,which are entirely formed of a magnetic material from protruding endparts (the surface side of the magnetic disk 10A: the upper end parts inFIG. 2) to base end parts (lower end parts in FIG. 2) thereof, andconcave parts 40 b, which are formed in between the convex parts 40 a.The concave parts 40 b are filled with a non-magnetic material 15 suchas SiO₂ to make the surface of the magnetic disk 10A flat. Note that onthe magnetic disk 10A, the formation regions of the convex parts 40 acorrespond to “recording regions”, and the formation regions of theconcave parts 40 b (the regions filled with the non-magnetic material15) correspond to “non-recording regions”. In addition, a protectivelayer 16 (DLC film) of diamond-like carbon (DLC) or the like with athickness of around 2 nm is formed on the surfaces of the non-magneticmaterial 15 that fills the concave parts 40 b and the magnetic layer 14(the convex parts 40 a). A lubricant (as one example, a Fomblinlubricant) is also applied onto the surface of the protective layer 16to protect both the magnetic head 3 and the magnetic disk 10A fromdamage.

The glass substrate 11 is formed in a disk shape with a thickness ofaround 0.6 mm by polishing the surface of a glass plate with a diameterof 2.5 inches. It should be noted that the substrate used for themagnetic disk 10A is not limited to a substrate of the glass materialdescribed above and it is possible to use a substrate formed in a diskshape using various types of non-magnetic materials such as aluminum orceramics. The soft magnetic layer 12 is formed as a thin film with athickness of around 100 nm to 200 nm by sputtering a soft magneticmaterial such as CoZrNb alloy. The intermediate layer 13 functions as anunderlayer for forming the magnetic layer 14 and is formed as a thinfilm with a thickness of around 40 nm by sputtering an intermediatelayer forming material such as Cr or a non-magnetic CoCr alloy. Themagnetic layer 14 constructs the concave/convex patterns 40 (data trackpatterns 40 t and servo patterns 40 sa shown in FIG. 4), with theconcave parts 40 b being formed by carrying out an etching process on alayer formed by sputtering a CoCrPt alloy, for example.

Here, as shown in FIG. 3, on the magnetic disk 10A, servo patternregions Asa are provided between the respective data recording regionsAt, and the data recording regions At and the servo pattern regions Asaare set so as to be alternately disposed in a direction of rotation (thedirection of the arrow R) of the magnetic disk 10A. The hard disk drive1 equipped with the magnetic disk 10A is constructed as described aboveso that the motor 2 rotates the magnetic disk 10A at a constant angularvelocity in accordance with control by the control unit 6. Accordingly,on the magnetic disk 10A, the length of the data recording regions Atalong the direction of rotation of the magnetic disk 10A and the lengthof the servo pattern regions Asa along the direction of rotation are setso as to increase as the distance from the center O increases inproportion to the length on the magnetic disk 10A that passes below themagnetic head 3 per unit time (i.e., the data recording regions At andthe servo pattern regions Asa become wider from an inner peripheryregion toward an outer periphery region). As a result, the length alongthe direction of rotation of data recording tracks (the convex parts 40a) formed inside the data recording regions At and the standard lengthsalong the direction of rotation of the convex parts 40 a and concaveparts 40 b used as the servo patterns 40 sa formed inside the servopattern regions Asa (for example, the lengths corresponding to a one-bitsignal) becomes longer from the inner periphery region to the outerperiphery region of the magnetic disk 10A.

Also, as shown in FIG. 4, data track patterns 40 t are formed in thedata recording regions At. Note that in FIG. 4 and in FIGS. 5, 16, and17 described later, the obliquely shaded regions show the formationregions of the convex parts 40 a (that is, the recording regions) in theconcave/convex patterns 40, while the white regions show the formationregions of the concave parts 40 b (that is, the non-recording regions)of the concave/convex patterns 40. Here, as shown in FIG. 5, each datatrack pattern 40 t is constructed of a large number of concentric orspiral convex parts 40 a (data recording tracks) centered on the centerO (see FIG. 3) and concave parts 40 b present between the respectiveconvex parts 40 a (“inter-track concave parts”). Note that although itis preferable for the center of rotation of the magnetic disk 10A andthe center O (“track pattern center” for the present invention) of thedata track patterns 40 t to match, in reality there is the risk of aminute displacement of around 30 μm to 50 μm being caused between thecenter of rotation of the magnetic disk 10A and the center O of the datatrack patterns 40 t due to manufacturing error. However, since trackingservo control can still be performed sufficiently for the magnetic head3 when a displacement of such magnitude is present, the center ofrotation and the center O can be thought of as effectively matching.Also, in each data recording region At of the magnetic disk 10A, as oneexample, the length of the convex parts 40 a (the data recording tracks)along the radial direction of the magnetic disk 10A is equal to thelength of the concave parts 40 b along the radial direction of themagnetic disk 10A. That is, the ratio of the widths is 1:1. In addition,on the magnetic disk 10A, the length along the radial direction of theconvex parts 40 a formed in the data recording regions At and the lengthalong the radial direction of the concave parts 40 b are setsubstantially equal from the inner periphery region to the outerperiphery region of the magnetic disk 10A.

On the other hand, as shown in FIG. 4, a servo pattern 40 sa, whichincludes a preamble pattern formed by a concave/convex pattern 40 in apreamble pattern region Ap, an address pattern formed by aconcave/convex pattern 40 in an address pattern region Aa, and burstpatterns formed by concave/convex patterns 40 in the burst patternregion Aba, is formed in each servo pattern region Asa. The burstpattern region Aba includes four burst regions, a first burst region Ab1a to a fourth burst region Ab4 a. In this case, patterns for positionaldetection to make the magnetic head 3 on-track to a desired track areformed by concave/convex patterns 40 in the first burst region Ab1 a tothe fourth burst region Ab4 a in the burst pattern region Aba. Morespecifically, as shown in FIG. 5, by forming a plurality of concaveparts 40 b (non-recording regions) along the direction of rotation ofthe magnetic disk 10A (the direction of the arrow R), regions in whichconvex parts 40 a (recording regions) and concave parts 40 b arealternately disposed along the direction of rotation and regions whereconvex parts 40 a are continuous along the direction of rotation areformed.

Also, as shown in FIG. 5, two sets of burst patterns BP1 a, BP2 acorresponding to “M sets of burst patterns” for the present inventionare formed in the burst pattern region Aba (an example where “M=2”).More specifically, a burst pattern BP1 a corresponding to one out of the“M sets of burst patterns” for the present invention is formed by theconcave/convex pattern 40 formed in the first burst region Ab1 a and theconcave/convex pattern 40 formed in the second burst region Ab2 a and aburst pattern BP2 a corresponding to another out of the “M sets of burstpatterns” for the present invention is formed by the concave/convexpattern 40 formed in the third burst region Ab3 a and the concave/convexpattern 40 formed in the fourth burst region Ab4 a. Also, the concaveparts 40 b formed in each burst pattern region Aba respectivelycorrespond to “burst signal units” for the present invention and areformed so as to have equal lengths L11 (referred to as “BW” for thepresent invention) along the radial direction of the magnetic disk 10A(the left-right direction in FIG. 5). Note that although an examplewhere three concave parts 40 b are disposed along the direction ofrotation in each of the burst regions from the first burst region Ab1 ato the fourth burst region Ab4 a has been illustrated for ease ofunderstanding the present invention, in reality ten to thirty concaveparts 40 b are formed in a line along the direction of rotation in eachburst region. In addition, the pattern formed in each burst region isnot limited to a pattern where a plurality of burst signal units aredisposed along the direction of rotation, and it is possible toconstruct a burst pattern by forming a single burst signal unit (aconcave part 40 b) along the direction of rotation in each burst region.

Here, on the magnetic disk 10A, a plurality of burst patterns BP1 a areformed along the radial direction inside the first burst region Ab1 aand the second burst region Ab2 a and a plurality of burst patterns BP2a are formed along the radial direction inside the third burst regionAb3 a and the fourth burst region Ab4 a. The rows of concave parts 40 bdisposed along the direction of rotation inside the burst regions Ab1 ato Ab4 a each construct two burst patterns BP1 a (or two burst patternsBP2 a). More specifically, as shown in FIG. 5, as one example, a row ofconcave parts 40 b disposed along the direction of rotation inside thefirst burst region Ab1 a constructs one burst pattern BP1 a togetherwith a row of concave parts 40 b inside the second burst region Ab2 apositioned closer to the inner periphery in the radial direction thansuch a row of concave parts 40 b and another burst pattern BP1 atogether with a row of concave parts 40 b inside the second burst regionAb2 a positioned closer to the outer periphery than such a row ofconcave parts 40 b.

Also, as shown in FIG. 5, on the magnetic disk 10A, the concave/convexpatterns 40 are formed in each burst pattern region Aba to form theburst patterns BP1 a, BP2 a so that the distance from the center O tothe burst signal units (as one example, the distance between the centerO and centers in the radial direction of the burst signal units (theconcave parts 40 b)) differs in each burst region from the first burstregion Ab1 a to the fourth burst region Ab4 a. Here, regarding the burstpattern BP1 a, the concave parts 40 b formed in the first burst regionAb1 a and the second burst region Ab2 a correspond to “two types ofburst signal units” for the present invention and regarding the burstpattern BP2 a, the concave parts 40 b formed in the third burst regionAb3 a and the fourth burst region Ab4 a correspond to “two types ofburst signal units” for the present invention. In addition, on themagnetic disk 10A, the concave/convex patterns 40 are formed in eachburst pattern region Aba so that the formation pitch along the radialdirection of the concave parts 40 b in each burst region out of thefirst burst region Ab1 a to the fourth burst region Ab4 a (a lengthequal to the distance between the centers in the radial direction of theconcave parts 40 b in each burst region: the length L12 in FIG. 5) isequal. Here, on the magnetic disk 10A, the length L12 is double thetrack pitch Tp (an example where “N=2” for “(2·M/N)·Track Pitch”).

Also, on the magnetic disk 10A, the concave parts 40 b are formed in thefirst burst region Ab1 a to the fourth burst region Ab4 a so that four(one example of “2·M”) centers C1 a, C2 a, . . . in the radial directionof the burst patterns BP1 a, BP2 a, . . . are present at intervals equalto half the track pitch Tp (i.e., “(1/N)·Track Pitch”) in a range whoselength L10 along the radial direction is produced by multiplying thetrack pitch Tp by (2·M/N) (i.e., “(2·M/N)·Track Pitch”: in this example,a length double the track pitch) where both ends of the length L10 inthe radial direction (positions shown by the dot-dash lines in FIG. 5)do not match the centers C1 a, C2 a, . . . in the radial direction ofthe burst patterns BP1 a, BP2 a, . . . (such range is referred to as a“predetermined range” for the present invention). On the magnetic disk10A, the concave/convex patterns 40 are formed in each burst patternregion Aba so that the center C1 a in the radial direction of a burstpattern BP1 a matches a center (track center) in the radial direction ofa data recording track (convex parts 40 a formed in the data recordingregions At) (i.e., the distance between the center C1 a of a burstpattern BP1 a and the center of a data recording track is “0”) and thedistance (length L15) between the center C2 a in the radial direction ofa burst pattern BP2 a and the center in the radial direction of a datarecording track is half the track pitch Tp.

The burst patterns BP1 a are formed so that the concave parts 40 bformed in the first burst region Ab1 a and the concave parts 40 b formedin the second burst region Ab2 a are separated from each other in thedirection of rotation via convex parts 40 a (one example where the burstpatterns BP1 a are formed so that “a first type of burst signal unitsand a second type of burst signal units out of the two types of burstsignal units do not overlap in the direction of rotation”). In addition,in the burst patterns BP1 a, the centers in the radial direction of theconcave parts 40 b formed in the first burst region Ab1 a and thecenters in the radial direction of the concave parts 40 b formed in thesecond burst region Ab2 a are separated in the radial direction by alength L13 equal to the track pitch Tp (“(M/N)·Track Pitch” for thepresent invention). In the burst patterns BP1 a, facing end parts out ofthe end parts in the radial direction of the concave parts 40 b formedin the first burst region Ab1 a and the concave parts 40 b formed in thesecond burst region Ab2 a are separated in the radial direction viaconvex parts 40 a by a length L14 that is narrower than the track pitchTp (“(M/N)·Track Pitch”). On the magnetic recording medium according tothe present invention, it is not necessary to separate the concave parts40 b in the first burst region Ab1 a and the concave parts 40 b in thesecond burst region Ab2 a by the length L14 in the radial direction inthe entire range from the inner periphery region to the outer peripheryregion, and it is possible to use a construction where the concave parts40 b are separated in the radial direction in only an arbitrary region.It is also possible for the length L14 to differ as desired inrespective regions from the inner periphery region to the outerperiphery region without the length L14 being set at the same lengthfrom the inner periphery region to the outer periphery region. Since thedetectable zone based on the PES widens as the length L14 increases, ifthere is the risk of proper tracking servo control being difficult dueto the detectable zone being narrow in the inner periphery of themagnetic disk 10A, for example, it is possible to use a constructionwhere the length L14 gradually increases on the magnetic disk 10A fromthe outer periphery to the inner periphery.

The burst patterns BP2 a are formed so that the concave parts 40 bformed in the third burst region Ab3 a and the concave parts 40 b formedin the fourth burst region Ab4 a are separated from each other in thedirection of rotation via convex parts 40 a (one example where the burstpatterns BP2 a are formed so that “a first type of burst signal unitsand a second type of burst signal units out of the two types of burstsignal units do not overlap in the direction of rotation”). In addition,in the burst patterns BP2 a, the centers in the radial direction of theconcave parts 40 b formed in the third burst region Ab3 a and thecenters in the radial direction of the concave parts 40 b formed in thefourth burst region Ab4 a are separated in the radial direction by thelength L13 equal to the track pitch Tp (“(M/N)·Track Pitch” for thepresent invention). In the burst patterns BP2 a, facing end parts out ofthe end parts in the radial direction of the concave parts 40 b formedin the third burst region Ab3 a and the concave parts 40 b formed in thefourth burst region Ab4 a are separated in the radial direction viaconvex parts 40 a by the length L14 that is narrower than the trackpitch Tp (“(M/N)·Track Pitch”).

On the magnetic recording medium according to the present invention, itis not necessary to separate the concave parts 40 b in the third burstregion Ab3 a and the concave parts 40 b in the fourth burst region Ab4 aby the length L14 in the radial direction in the entire range from theinner periphery region to the outer periphery region, and it is possibleto use a construction where the concave parts 40 b are separated in theradial direction in only an arbitrary region. It is also possible forthe length L14 to differ as desired in respective regions from the innerperiphery region to the outer periphery region without the length L14being set at the same length from the inner periphery region to theouter periphery region. Since the detectable zone based on the PESwidens as the length L14 increases, if there is the risk of propertracking servo control being difficult due to the detectable zone beingnarrow in the inner periphery of the magnetic disk 10A, for example, itis possible to use a construction where the length L14 graduallyincreases on the magnetic disk 10A from the outer periphery to the innerperiphery. Note that to carry out the recording and reproducing ofrecording data properly, the actuator 3 b described above (as oneexample, a VCM (Voice Coil Motor)) is normally designed so that thetracking precision (mechanical precision) is 5% or below of the trackpitch Tp. In other words, during the recording and reproducing ofrecording data, the magnetic head 3 driven by the actuator 3 bconstantly makes minute movements in the radial direction of themagnetic disk 10A in a predetermined range with an upper limit of around5% of the track pitch Tp. Accordingly, to reliably widen the detectablezone for detecting the position of the magnetic head 3 based on the PES,the length L14 (the distance in the radial direction between the twotypes of burst signal units that construct a burst pattern) in the burstpatterns BP1 a, BP2 a described above should preferably be set at atleast 5% of the track pitch Tp.

The above magnetic disk 10A is formed as described above so that both“M” and “N” for the present invention are “2”. Accordingly, if thevalues of “M=2” and “N=2” are substituted into a condition“(M+1)·Tp/N−BW≦Wr≦(M−1)·Tp/N+BW” to be satisfied by the magneticrecording medium according to the present invention, the magnetic disk10A will satisfy the above condition so long as the width Wr of thereproducing element Ra of the magnetic head 3 is equal to or greaterthan a width Wr1 a (see FIG. 5) that is “ 3/2 times the track pitch Tpminus the length L11” and equal to or less than a width Wr2 a (see FIG.5) that is “½ times the track pitch Tp plus the length L11”. In thepresent specification, the case where the width Wr of the reproducingelement Ra of the magnetic head 3 is “ 3/2 times the track pitch Tpminus the length L11” is described below as one example. Note that thewidth (the minimum width Wr1 a and the maximum width Wr2 a) of thereproducing element Ra of the magnetic head 3 when using the magneticdisk 10A will be described in detail later.

Next, the method of manufacturing the magnetic disk 10A will bedescribed.

When manufacturing the magnetic disk 10A described above, a preform 20shown in FIG. 6 and a stamper 30 shown in FIG. 7 are used. Here, asshown in FIG. 6, the preform 20 is constructed by forming the softmagnetic layer 12, the intermediate layer 13, and the magnetic layer 14in the mentioned order on the glass substrate 11, with a mask layer 17and a resin layer (resist layer) 18 with a thickness of around 80 nmbeing formed on the magnetic layer 14. On the other hand, the stamper 30is one example of a “stamper for manufacturing a magnetic recordingmedium” according to the present invention and as shown in FIG. 7 hasformed thereupon a concave/convex pattern 39 capable of forming aconcave/convex pattern 41 for forming the concave/convex patterns 40(the data track patterns 40 t and the servo patterns 40 sa) of themagnetic disk 10A so that the magnetic disk 10A can be manufactured byimprinting. In this case, the concave/convex pattern 39 of the stamper30 is formed so that convex parts 39 a correspond to the concave parts40 b (non-recording regions as “one of the regions” for the presentinvention) in the concave/convex patterns 40 and concave parts 39 bcorrespond to the convex parts 40 a (recording regions as “other of theregions” for the present invention) in the concave/convex patterns 40 ofthe magnetic disk 10A. Note that since it is possible to manufacture thestamper 30 using a variety of well-known manufacturing methods, detaileddescription of the method of manufacturing the stamper 30 has beenomitted.

First, as shown in FIG. 8, the concave/convex pattern 39 of the stamper30 is transferred to the resin layer 18 of the preform 20 by imprinting.More specifically, by pressing the surface of the stamper 30 on whichthe concave/convex pattern 39 is formed onto the resin layer 18 of thepreform 20, the convex parts 39 a of the concave/convex pattern 39 arepressed into the resin layer 18 of the preform 20. When doing so, theresist (resin layer 18) at positions where the convex parts 39 a arepressed in moves inside the concave parts 39 b of the concave/convexpattern 39. After doing so, the stamper 30 is separated from the preform20 and by carrying out an oxygen plasma process to remove resin (notshown) remaining on the base surfaces, as shown in FIG. 9, aconcave/convex pattern 41 composed of the resin layer 18 is formed onthe mask layer 17 of the preform 20. Here, the height of the respectiveconvex parts 41 a in the concave/convex pattern 41 (or the depth of therespective concave parts 41 b) is around 130 nm.

Next, by carrying out an etching process using the concave/convexpattern 41 (the resin layer 18) described above as a mask, the masklayer 17 exposed from the mask (the convex parts 41 a) at the base partsof the concave parts 41 b in the concave/convex pattern 41 is etched asshown in FIG. 10 to form a concave/convex pattern 42 including convexparts 42 a and concave parts 42 b in the mask layer 17 of the preform20. After this, by carrying out an etching process with theconcave/convex pattern 42 (the mask layer 17) as a mask, the magneticlayer 14 exposed from the mask (the convex parts 42 a) at the base partsof the concave parts 42 b of the concave/convex pattern 42 is etched asshown in FIG. 11 to form the concave/convex patterns 40 including theconvex parts 40 a and the concave parts 40 b in the magnetic layer 14 ofthe preform 20. Next, by carrying out a selective etching process on themask layer 17 remaining on the convex parts 40 a, the remaining masklayer 17 is completely removed to expose the protruding end surfaces ofthe convex parts 40 a. By doing so, the data track patterns 40 t and theservo patterns 40 sa (the concave/convex patterns 40) are formed on theintermediate layer 13.

Next, as shown in FIG. 12, SiO₂ is sputtered as the non-magneticmaterial 15. When doing so, a sufficient amount of non-magnetic material15 is sputtered to completely fill the concave parts 40 b with thenon-magnetic material 15 and to form a layer of the non-magneticmaterial 15 with a thickness of around 60 nm, for example, on the convexparts 40 a. After this, ion beam etching is carried out on the layer ofthe non-magnetic material 15 on the magnetic layer 14 (on the convexparts 40 a and on the concave parts 40 b). When doing so, the ion beametching continues until the protruding end surfaces of the convex parts40 a are exposed from the non-magnetic material 15. By doing so, the ionbeam etching is completed on the layer of the non-magnetic material 15as shown in FIG. 13 to make the surface of the preform 20 flat. Next,after the protective layer 16 has been formed by forming a thin film ofdiamond-like carbon (DLC) by CVD so as to cover the surface of thepreform 20, a Fomblin lubricant is applied to the surface of theprotective layer 16 with an average thickness of around 2 nm, forexample. By doing so, as shown in FIG. 2, the magnetic disk 10A iscompleted.

As shown in FIG. 14, as one example, the burst patterns BP1 a are formedon the magnetic disk 10A so that the end parts in the radial directionof the concave parts 40 b formed in the first burst region Ab1 a and theend parts in the radial direction of the concave parts 40 b formed inthe second burst region Ab2 a are separated and do not overlap oneanother in the radial direction on both sides of track centers (thecenters of data recording tracks in the radial direction). Accordingly,on the magnetic disk 10A, the length L11 along the radial direction ofthe concave parts 40 b (burst signal units) formed in the burst regionsAb1 a, Ab2 a is shorter than the track pitch Tp. As a result, when theposition of the magnetic head 3 relative to the magnetic disk 10Achanges and the magnetic head 3 (the reproducing element Ra) moves withrespect to the magnetic disk 10A in the direction of the arrow A fromthe position P1 to the position P2, for example, the output level of theoutput signal from the magnetic head 3 in the first burst region Ab1 ais shown by the solid line Aa. Also, when the magnetic head 3 moves withrespect to the magnetic disk 10A in the direction of the arrow B fromthe position P3 to the position P4, for example, the output level of theoutput signal from the magnetic head 3 in the second burst region Ab2 ais shown by the solid line Ba. In this case, if the output signal shownby the solid line Aa is set as S1 and the output signal shown by thesolid line Ba is set as S2, the PES obtained from the burst pattern BP1a is “(S1−S2)/(S1+S2)”. Accordingly, the PES obtained from the burstpattern BP1 a has the characteristics shown by the solid line in FIG.14.

On the other hand, on the conventional magnetic disk 10 x 1, asdescribed earlier, the burst patterns are formed so that both end partsin the radial direction of the servo patterns Ps1, Ps2 match the trackcenters, that is, both end parts are positioned at the track centers.Accordingly, on the conventional magnetic disk 10 x 1, the width Tsalong the radial direction of the servo patterns Ps1, Ps2 (burst signalunits) is equal to the track pitch Tp. As a result, when the position ofthe magnetic head with respect to the conventional magnetic disk 10 x 1changes and the magnetic head (the reproducing element Rx) movesrelative to the magnetic disk 10 x 1 in the direction of the arrow Afrom the position P1 to the position P2, for example, the output levelof the output signal from the magnetic head is shown by the dot-dashline Ax. Also, when the magnetic head moves relative to the magneticdisk 10 x 1 in the direction of the arrow B from the position P3 to theposition P4, for example, the output level of the output signal from themagnetic head is shown by the dot-dash line Bx. As a result, the PESobtained from the servo patterns Ps1, Ps2 of the conventional magneticdisk 10 x 1 has the characteristics shown by the dot-dash line in FIG.14.

In this case, when the magnetic head 3 has moved in the direction of thearrow C from a state where the magnetic head 3 is positioned at theposition P0 (in this example, the track center), with the conventionalmagnetic disk 10 x 1, the range in which the position of the magnetichead can be detected based on the PES is the range from the position P0to the position Pxc. On the other hand, with the magnetic disk 10A, thecontrol unit 6 can detect the position of the magnetic head 3 based onthe PES in a wide range from the position P0 to the position Pac. Also,when the magnetic head 3 has moved from the position P0 in the directionof the arrow D, with the conventional magnetic disk 10 x 1, the range inwhich the position of the magnetic head can be detected based on the PESis the range from the position P0 to the position Pxd. On the otherhand, with the magnetic disk 10A, the control unit 6 can detect theposition of the magnetic head 3 based on the PES in a wide range fromthe position P0 to the position Pad. Accordingly, with the magnetic disk10A, even when the magnetic head 3 is greatly displaced from the trackcenter, it is possible to detect such displacement based on the PES andmake the magnetic head 3 on-track to a desired track.

On the magnetic disk 10A, as described above, the data track patterns 40t and the servo patterns 40 sa are formed so that the width Wr of themagnetic head 3, the formation pitch (the track pitch Tp) along theradial direction of the convex parts 40 a in the data track patterns 40t, and the length L11 (“BW” for the present invention) along the radialdirection of the concave parts 40 b formed in the first burst region Ab1a to the fourth burst region Ab4 a satisfy the condition“(M+1)·Tp/N−BW≦Wr≦(M−1)·Tp/N+BW”. Accordingly, with the magnetic disk10A, the width Wr of the reproducing element Ra can be defined withcomparatively freely without the width Wr of the reproducing element Rabeing primarily determined by the lengths of the various parts of thedata track patterns 40 t and the servo patterns 40 sa. In other words,unlike the conventional magnetic disk 10 x 1, the lengths of the variousparts of the data track patterns 40 t and the servo patterns 40 sa canbe set without being primarily determined by the width Wr of thereproducing element Ra of the magnetic head 3.

More specifically, as shown in FIG. 15, on this magnetic disk 10A, thelength L12 that is the formation pitch along the radial direction of theconcave parts 40 b formed in the first burst region Ab1 a is double thetrack pitch Tp (i.e., “(M/N)·Tp·2”). In this case, the length L12described above is equal to the length L10 (the length along the radialdirection of the “predetermined range” for the present invention). Thismeans that on the magnetic disk 10A, four (i.e., “2·M”) centers C1 a, C2a, . . . in the radial direction of the burst patterns BP1 a, BP2 a, . .. are present at intervals of half the track pitch Tp (intervals of“1/N·Track Pitch”) within a range of the length L12. More specifically,the concave parts 40 b (burst signal units) in the first burst regionAb1 a to the fourth burst region Ab4 a are formed so that the centers C1a, C2 a, . . . of the burst patterns BP1 a, BP2 a, . . . are presentnear both ends of the convex parts 40 a in the radial direction.Accordingly, in the first burst region Ab1 a, for example, the centersC1 a in the radial direction of two burst patterns BP1 a are present inthe range of the length L12 described above that is the formation pitchalong the radial direction of the concave parts 40 b. Also, the centersC1 a, C2 a in the radial direction of two sets (M sets) of burstpatterns BP1 a, BP2 a, that is, a total of four (2·M) centers C1 a, C2a, . . . are present in the range of the length L12.

Accordingly, on the magnetic disk 10A, a length L16 along the radialdirection of the range in which tracking servo control is to beperformed for the magnetic head 3 based on the PES obtained from oneburst pattern BP1 a, for example, is one quarter (1/(2·M)) of the lengthL12 described above. In this case, the length L16 is the half the trackpitch Tp ((M/N)·Tp·2/(2·M)=(1/N)·Tp), and on the magnetic disk 10A, halfthe track pitch Tp is the length L16 that is equal to the width of thedata recording tracks and the width of the inter-track concave parts.That is, on the magnetic disk 10A, the range for which tracking servocontrol is to be carried out for the magnetic head 3 based on the PESobtained from the burst pattern BP1 a is within the range of the lengthL16 that is equal to the width of the data recording tracks and thewidth of the inter-track concave parts. Also, the length L14 that is thedistance along the radial direction between the end parts of the concaveparts 40 b formed in the first burst region Ab1 a and the end parts ofthe concave parts 40 b formed in the second burst region Ab2 a is alength “(M/N)·Tp−BW” produced by subtracting the length L11 from halfthe length L12, and is equal to a length produced by subtracting thelength L11 from the track pitch Tp.

Here, in a state where the reproducing element Ra is located at theposition P5 that is one end part of the range (length L16) for whichtracking servo control is to be carried out (i.e., in a state where thecenter in the width direction of the reproducing element Ra is above theposition P5), if the width Wr of the reproducing element Ra is narrowerthan the width Wr1 a in FIG. 15, a gap is produced in the radialdirection (the direction of tracking servo control) between the end partof the reproducing element Ra and the end parts of the concave parts 40b formed in the first burst region Ab1 a. Since this gap is a dead zone,the width Wr of the reproducing element Ra needs to be equal to orgreater than the width Wr1 a shown in FIG. 15. As shown in FIG. 15, thewidth Wr1 a is double the total of the length L14 a and the length L16a. Here, the length L14 a is half of the length L14 and the length L16 ais half of the length L16 (i.e., Tp/(2·N)). That is, half the width Wr1a is produced by subtracting half the length L11 from the total of (i)half the length (the length L14 a: “(M/N)·Tp/2−BW/2”) produced bysubtracting the length L11 (the length L14) from the track pitch Tp and(ii) half the length (the length L16 a: Tp/(2·N)) of half the trackpitch Tp (the length L16), or in other words, by subtracting half thelength L11 from ¾ of the track pitch Tp. Accordingly, the width Wr1 a isa length produced by subtracting the length L11 (BW) from 3/2 times thetrack pitch Tp (i.e., (M+1)·Tp/N), which matches the term“(M+1)·Tp/N−BW” in the condition of the present invention.

On the other hand, in a state where the reproducing element Ra islocated at the position P6 at another end part of the range for whichtracking servo control is to be carried out (the length L16) (i.e., in astate where the center in the width direction of the reproducing elementRa is above the position P6), if the width Wr of the reproducing elementRa is wider than the width Wr2 a shown in FIG. 15, the end part of thereproducing element Ra protrudes in the radial direction (the directionin which tracking servo control is carried out) from the end parts ofthe concave parts 40 b formed in the first burst region Ab1 a. Since theprotruding amount is a dead zone, the width Wr of the reproducingelement Ra needs to be equal to or below the width Wr2 a shown in FIG.15. The width Wr2 a is double a length produced by subtracting thelength L17 from the length L11. Here, the length L17 is a lengthproduced by subtracting the length L14 a from the length L16 a, that is,a length produced by subtracting (Tp−BW)·(M/N)·(½), which is half alength produced by subtracting the length L11 from the track pitch Tp,from the length Tp/(2·N) that is half the length L16 (L16=half the trackpitch Tp). That is, half the width Wr2 a is a total(“BW−Tp/(2·N)+(M/N)·Tp/2−BW/2”=“(M−1)·Tp/(2·N)+BW/2”) of (i) a lengthproduced by subtracting the length (Tp/(2·N) that is ¼ of the trackpitch Tp from the length L11 and (ii) the length L14 a. Accordingly, thewidth Wr2 a is the total of the length (M−1)·Tp/N, which is half thetrack pitch Tp, and the length L11(BW), and therefore matches the“(M−1)·Tp/N+BW” term in the condition of the present invention.

As described above, the track pitch Tp and the length L11 on themagnetic disk 10A are set so as to satisfy the condition“(M+1)·Tp/N−BW≦Wr≦(M−1)·Tp/N+BW”. Accordingly, for reproducing elementsRa of various widths Wr in a range from the width Wr1 a to the width Wr2a set as described above, with the magnetic disk 10A, the position ofthe magnetic head 3 (the reproducing element Ra) above the magnetic disk10A can be specified without producing dead zones. Here, with themagnetic disk 10A, the burst patterns BP1 a, BP2 a are formed in theburst pattern regions Aba so that the interval along the radialdirection between the centers C1 a, C2 a, . . . in the radial directionof the burst patterns BP1 a, BP2 a . . . is (½)·track pitch Tp (anexample where N=2 for “1/N track pitch”). Accordingly, unlike theconventional magnetic disks 10 x 1, 10 x 2 where the burst patterns areformed so that intervals along the radial direction between the centersin the radial direction of the burst patterns produced by the servopatterns Ps1, Ps2 or the servo patterns Ps3, Ps4 functioning as a pairare equal to the track pitch Tp (where “N=1”), as described above, evenif the width Wr of the reproducing element Ra is narrower than the trackpitch Tp, it is still possible to specify the position of the magnetichead 3 (the reproducing element Ra) above the magnetic disk 10A withouta dead zone being produced. This means that by using a reproducingelement Ra whose width Wr is narrower than the track pitch Tp asnecessary, it is possible to avoid “side reading”.

Also, on the magnetic recording medium according to the presentinvention, the intervals between the centers in the radial direction ofthe burst patterns is set at “(1/N)·Track Pitch”, where N is a naturalnumber of two or higher. Here, when the value “N” is set at anon-natural number, the positional relationship in the radial directionbetween a track center of a data recording track and a position wherethe value of the PES obtained from a burst pattern is “0” (the positionof a center in the radial direction of the burst pattern) will differfor each data recording track. As a result, the value of PES when themagnetic head (the reproducing element) is positioned at a track centerwill differ for each data recording track, for example, which makes aprocess complex to position the reproducing element at a track center ofa desired data recording track based on the value of the PES. On theother hand, when the value “N” is a natural number, the positionalrelationship in the radial direction between a track center of a datarecording track and a position where the value of the PES is “0” is thesame for every data recording track. By doing so, since the value of thePES when the magnetic head (the reproducing element) is positioned at atrack center is the same for every data recording track, for example, aprocess that positions the reproducing element at a track center basedon the value of the PES can be carried out extremely easily for any ofthe recording tracks. Also, like the magnetic disk 10A described above,by having the centers C1 a along the radial direction of the burstpatterns BP1 a match the track centers, it is possible to specify thatthe reproducing element Ra is positioned at a track center when thevalue of the PES is “0”. By doing so, it is possible to easily positionthe reproducing element Ra on a track center without a complex processbeing necessary.

In this way, according to the magnetic disk 10A and the hard disk drive1, by forming the burst signal units so that the M (in the aboveexample, 2) sets of burst patterns BP1 a, BP2 a, . . . that each havetwo types of burst signal units constructed of concave parts 40 b(non-recording regions) are formed in the direction of rotation, and sothat in at least one part (in the above example, the entire region) outof the regions from the inner periphery region to the outer peripheryregion, facing end parts in the radial direction of the concave parts 40b formed in the first burst region Ab1 a and the second burst region Ab2a are separated in the radial direction via the convex parts 40 a(recording regions) and facing end parts in the radial direction of theconcave parts 40 b formed in the third burst region Ab3 a and the fourthburst region Ab4 a are separated in the radial direction via the convexparts 40 a (recording regions), it is possible to sufficiently widen thedetectable zone for detecting the position of the magnetic head 3 (thereproducing element Ra) based on the PES, and as a result, even if thereare variations in the output signal outputted from the magnetic head 3corresponding to the burst patterns BP1 a, BP2 a, . . . due to noise orthe like, it will still be possible to reliably detect positionaldisplacements of the magnetic head 3 and carry out proper tracking servocontrol. Also, unlike the conventional magnetic disk 10 x 1 where thereis only one set of burst patterns (i.e., where M=1), there is no needfor the width Wr of the reproducing element Ra of the magnetic head 3 tomatch the track pitch Tp, and therefore the data track patterns 40 t andthe servo patterns 40 sb can be designed with increased freedom. Also,unlike the conventional magnetic disk 10 x 2 where there are two (M=2)burst patterns but the centers in the radial direction of the burstpatterns are disposed at intervals equal to the track pitch, the widthWr of the reproducing element Ra does not need to be wider than thetrack pitch Tp, and therefore it is possible to sufficiently suppress“side reading”.

According to the hard disk drive 1 equipped with the magnetic disk 10A,by forming the burst patterns BP1 a, BP2 a of the magnetic disk 10A sothat the condition to be satisfied by the magnetic recording mediumaccording to the present invention “(M+1)·Tp/N−BW≦Wr≦(M−1)·Tp/N+BW” issatisfied, by using a magnetic head 3 with a reproducing element Rawhose width satisfies the above condition, it is possible tosufficiently widen the detectable zone for detecting the position of themagnetic head 3 (the reproducing element Ra) based on the PES withoutproducing dead zones for the burst patterns, which makes it possible tocarry out proper tracking servo control. Here, unlike the conventionalmagnetic disk 10 x 1, since the track pitch Tp and the length L11 alongthe radial direction of the burst signal units (the concave parts 40 b)are not primarily determined by the width of the reproducing element Ra,the data track patterns and the servo patterns can be designed withincreased freedom. By doing so, it is possible to suitably change thetrack pitch Tp and the length L11 along the radial direction of theburst signal units (the concave parts 40 b) in accordance with objectssuch as increasing the track density and avoiding side reading. Also,unlike the conventional magnetic disk 10 x 2, the width Wr of thereproducing element Ra does not need to be made wider than the trackpitch Tp, and therefore side reading can be sufficiently avoided. Bydoing so, it is possible to provide a hard disk drive 1 equipped with amagnetic disk 10A capable of high-density recording and not susceptibleto reproduction errors.

In addition, according to the stamper 30 described above, by providing aconcave/convex pattern 39 including convex parts 39 a formedcorresponding to the concave parts 40 b (non-recording regions) of theconcave/convex patterns 40 of the magnetic disk 10A and concave parts 39b formed corresponding to the convex parts 40 a (recording regions) ofthe concave/convex patterns 40 of the magnetic disk 10A, it is possibleto easily manufacture, using a method such as imprinting, a magneticdisk 10A with burst patterns BP1 a, BP2 a, . . . where the detectablezone for detecting the position of the magnetic head 3 based on the PESis sufficiently wide.

Next, an example where a magnetic disk 10B that is another example of amagnetic recording medium according to the present invention is providedin the hard disk drive 1 will be described with reference to thedrawings. Note that component elements that are the same as the magneticdisk 10A described above have been assigned the same reference numeralsand duplicated description thereof has been omitted.

As shown in FIG. 16, the magnetic disk 10B is constructed so that servopattern regions Asb are set between the data recording regions At inplace of the servo pattern regions Asa of the magnetic disk 10A. Here,in place of the burst pattern region Aba of the magnetic disk 10A, eachservo pattern region Asb has a burst pattern region Abb including afirst burst region Ab1 b to the fourth burst region Ab4 b. In the firstburst region Ab1 b to the fourth burst region Ab4 b of the burst patternregion Abb, patterns for detecting the position of the magnetic head 3to make the magnetic head 3 on-track to a desired track are formed bythe concave/convex patterns 40. More specifically, as shown in FIG. 17,by forming a plurality of convex parts 40 a along the direction ofrotation (the direction of the arrow R) of the magnetic disk 10B,regions in which the concave parts 40 b and the convex parts 40 a arealternately disposed along the direction of rotation and regions inwhich the concave parts 40 b are continuous in the direction of rotationare formed. Note that on the magnetic disk 10B, the formation regions ofthe convex parts 40 a correspond to “recording regions” and theformation regions of the concave parts 40 b (i.e., regions filled withthe non-magnetic material 15) correspond to “non-recording regions”.

Also, as shown in FIG. 17, two (an example where M=2) sets of burstpatterns BP1 b, BP2 b that correspond to the “M burst patterns” for thepresent invention are formed in the burst pattern region Abb. Morespecifically, the burst pattern BP1 b corresponding to one out of the Msets of burst patterns for the present invention is composed of theconcave/convex pattern 40 formed in the first burst region Ab1 b and theconcave/convex pattern 40 formed in the second burst region Ab2 b, andthe burst pattern BP2 b corresponding to another out of the M sets ofburst patterns for the present invention is composed of theconcave/convex pattern 40 formed in the third burst region Ab3 b and theconcave/convex pattern 40 formed in the fourth burst region Ab4 b. Theconvex parts 40 a formed in the burst pattern region Abb correspond tothe “burst signal units” for the present invention and are formed so asto have an equal length L21 (“BW” for the present invention) along theradial direction (the left-right direction in FIG. 17) of the magneticdisk 10B. Note that although in FIG. 17, an example where three convexparts 40 a are disposed along the direction of rotation in each of theburst regions from the first burst region Ab1 b to the fourth burstregion Ab4 b has been illustrated for ease of understanding the presentinvention, in reality ten to thirty convex parts 40 a are formed in aline along the direction of rotation in each burst region. In addition,the pattern formed in each burst region is not limited to a patternwhere a plurality of burst signal units are disposed along the directionof rotation, and it is possible to construct a burst pattern by forminga single burst signal unit (a convex part 40 a) along the direction ofrotation in each burst region.

Here, on the magnetic disk 10B, a plurality of burst patterns BP1 b areformed along the radial direction inside the first burst region Ab1 band the second burst region Ab2 b and a plurality of burst patterns BP2b are formed along the radial direction inside the third burst regionAb3 b and the fourth burst region Ab4 b. The rows of convex parts 40 adisposed along the direction of rotation inside the burst regions Ab1 bto Ab4 b each construct two burst patterns BP1 b (or two burst patternsBP2 b). More specifically, as shown in FIG. 17, as one example, a row ofconvex parts 40 a disposed along the direction of rotation inside thefirst burst region Ab1 b constructs one burst pattern BP1 b togetherwith a row of convex parts 40 a inside the second burst region Ab2 bpositioned closer to the inner periphery in the radial direction thansuch a row of convex parts 40 a and another burst pattern BP1 b togetherwith a row of convex parts 40 a inside the second burst region Ab2 bpositioned closer to the outer periphery in the radial direction thansuch a row of convex parts 40 a.

Also, as shown in FIG. 17, on the magnetic disk 10B, the concave/convexpatterns 40 are formed in each burst pattern region Abb to form theburst patterns BP1 b, BP2 b so that the distance from the center O tothe burst signal units (as one example, the distance between the centerO and a center in the radial direction of the burst signal units (theconvex parts 40 a)) differs in each burst region from the first burstregion Ab1 b to the fourth burst region Ab4 b. Here, regarding the burstpattern BP1 b, the convex parts 40 a formed in the first burst regionAb1 b and the second burst region Ab2 b correspond to “two types ofburst signal units” for the present invention and regarding the burstpattern BP2 b, the convex parts 40 a formed in the third burst regionAb3 b and the fourth burst region Ab4 b correspond to “two types ofburst signal units” for the present invention. In addition, on themagnetic disk 10B, the concave/convex patterns 40 are formed in eachburst pattern region Abb so that the formation pitch along the radialdirection of the convex parts 40 a in each burst region from the firstburst region Ab1 b to the fourth burst region Ab4 b (a length equal tothe distance between the centers in the radial direction of the convexparts 40 a in each burst region: the length L22 in FIG. 17) is equal.Here, on the magnetic disk 10B, the length L22 is double the track pitchTp (an example where “N=2” for “(2·M/N)·Track Pitch”).

Also, on the magnetic disk 10B, the convex parts 40 a are formed in thefirst burst region Ab1 b to the fourth burst region Ab4 b so that four(one example of “2·M”) centers C1 b, C2 b, . . . in the radial directionof the burst patterns BP1 b, BP2 b, . . . are present at intervals equalto half the track pitch Tp (i.e., “(1/N)·Track Pitch”) in a range whoselength L20 along the radial direction is produced by multiplying thetrack pitch Tp by (2·M/N) (i.e., “(2·M/N)·Track Pitch”: in this example,double the track pitch) where both ends of the length L20 in the radialdirection (positions shown by the dot-dash lines in FIG. 17) do notmatch the centers C1 b, C2 b, . . . in the radial direction of the burstpatterns BP1 b, BP2 b, . . . (such range is referred to as a“predetermined range” for the present invention). On the magnetic disk10B, the concave/convex patterns 40 are formed in each burst patternregion Abb so that the center C1 b in the radial direction of the burstpattern BP1 b matches a center (track center) in the radial direction ofa data recording track (convex parts 40 a formed in the data recordingregions At) (i.e., the distance between the center C1 b of the burstpattern BP1 b and the center of the data recording track is “0”) and thedistance (length L25) between the center C2 b in the radial direction ofa burst pattern BP2 b and the center in the radial direction of a datarecording track is half the track pitch Tp.

The burst patterns BP1 b are formed so that the convex parts 40 a formedin the first burst region Ab1 b and the convex parts 40 a formed in thesecond burst region Ab2 b are separated from each other in the directionof rotation via concave parts 40 b (one example where the burst patternsBP1 b are formed so that “a first type of burst signal units and asecond type of burst signal units out of the two types of burst signalunits do not overlap in the direction of rotation”). In addition, in theburst patterns BP1 b, the centers in the radial direction of the convexparts 40 a formed in the first burst region Ab1 b and the centers in theradial direction of the convex parts 40 a formed in the second burstregion Ab2 b are separated in the radial direction by a length L23 equalto the track pitch Tp (“(M/N)·Track Pitch” for the present invention).In the burst patterns BP1 b, the concave/convex patterns 40 are formedso that end regions including facing end parts out of the end parts inthe radial direction of the convex parts 40 a formed in the first burstregion Ab1 a and the convex parts 40 a formed in the second burst regionAb2 b overlap in the radial direction by a length L24 that is narrowerthan the track pitch Tp (“(M/N)·Track Pitch”). Here, on the magneticrecording medium according to the present invention, it is not necessaryfor end regions of the convex parts 40 a in the first burst region Ab1 band end regions of the convex parts 40 a of the second burst region Ab2b to overlap by the length L24 in the radial direction in the entirerange from the inner periphery region to the outer periphery region, andit is possible to use a construction where the end regions of the convexparts 40 a overlap in the radial direction in only an arbitrary region.It is also possible for the length L24 to differ as desired inrespective regions from the inner periphery region to the outerperiphery region without the length L24 being set at the same lengthfrom the inner periphery region to the outer periphery region. Since thedetectable zone based on the PES widens as the length L24 increases, ifthere is the risk of proper tracking servo control being difficult dueto the detectable zone being narrow in the inner periphery of themagnetic disk 10B, for example, it is possible to use a constructionwhere the length L24 gradually increases on the magnetic disk 10B fromthe outer periphery to the inner periphery.

The burst patterns BP2 b are formed so that the convex parts 40 a formedin the third burst region Ab3 b and the convex parts 40 a formed in thefourth burst region Ab4 b are separated from each other in the directionof rotation via concave parts 40 b (one example where the burst patternsBP2 b are formed so that “a first type of burst signal units and asecond type of burst signal units out of the two types of burst signalunits do not overlap in the direction of rotation”). In addition, in theburst patterns BP2 b, the centers in the radial direction of the convexparts 40 a formed in the third burst region Ab3 b and the centers in theradial direction of the convex parts 40 a formed in the fourth burstregion Ab4 b are separated in the radial direction by the length L23equal to the track pitch Tp (“(M/N)·Track Pitch” for the presentinvention). In the burst patterns BP2 b, the concave/convex patterns 40are formed so that end regions including facing end parts out of the endparts in the radial direction of the convex parts 40 a formed in thethird burst region Ab3 b and the convex parts 40 a formed in the fourthburst region Ab4 b overlap in the radial direction by the length L24that is narrower than the track pitch Tp (“(M/N)·Track Pitch”).

Here, on the magnetic recording medium according to the presentinvention, it is not necessary for end regions of the convex parts 40 ain the third burst region Ab3 b and end regions of the convex parts 40 ain the fourth burst region Ab4 b to overlap by the length L24 in theradial direction in the entire range from the inner periphery region tothe outer periphery region, and it is possible to use a constructionwhere the end regions of the convex parts 40 a overlap in the radialdirection in only an arbitrary region. It is also possible for thelength L24 to differ as desired in respective regions from the innerperiphery region to the outer periphery region without the length L24being set at the same length from the inner periphery region to theouter periphery region. Since the detectable zone based on the PESwidens as the length L24 increases, if there is the risk of propertracking servo control being difficult due to the detectable zone beingnarrow in the inner periphery of the magnetic disk 10B, for example, itis possible to use a construction where the length L24 graduallyincreases on the magnetic disk 10B from the outer periphery to the innerperiphery. Note that to carry out the recording and reproducing ofrecording data properly, the actuator 3 b described above (as oneexample, a VCM) is normally designed so that the tracking precision(mechanical precision) is 5% or below of the track pitch Tp. In otherwords, during the recording and reproducing of recording data, themagnetic head 3 driven by the actuator 3 b constantly makes minutemovements in the radial direction of the magnetic disk 10B in apredetermined range with an upper limit of around 5% of the track pitchTp. Accordingly, to reliably widen the detectable zone for detecting theposition of the magnetic head 3 based on the PES, the length L24 (theamount by which the two types of burst signal units that construct aburst pattern overlap in the radial direction) in the burst patterns BP1b, BP2 b described above should preferably be at least 5% of the trackpitch Tp.

The above magnetic disk 10B is formed as described above so that both“M” and “N” for the present invention are “2”. Accordingly, if thevalues of “M=2” and “N=2” are substituted into a condition“(1−M)·Tp/N+BW≦Wr≦(3·M−1)·Tp/N−BW” to be satisfied by the magneticrecording medium according to the present invention, the magnetic disk10B will satisfy the above condition so long as the width Wr of areproducing element Rb of the magnetic head 3 is equal to or greaterthan a width Wr1 b that is “a length produced by subtracting half thetrack pitch Tp from the length L21” (see FIG. 17) and equal to or lessthan a width Wr2 b that is “a length produced by subtracting the lengthL21 from 5/2 times the track pitch Tp” (see FIG. 17). In the presentspecification, as one example, the case where the width Wr of thereproducing element Rb of the magnetic head 3 is “the length L21 minushalf the track pitch Tp” is described. Note that the width (the minimumwidth Wr1 b and the maximum width Wr2 b) of the reproducing element Rbof the magnetic head 3 when using the magnetic disk 10B is described indetail later.

When manufacturing the magnetic disk 10B described above, the preform 20shown in FIG. 6 and the stamper 30 shown in FIG. 7 are used in the sameway as when manufacturing the magnetic disk 10A described above. Thestamper 30 for manufacturing the magnetic disk 10B is another example ofa “stamper for manufacturing a magnetic recording medium” according tothe present invention and has formed thereupon a concave/convex pattern39 that can form a concave/convex pattern 41 for forming theconcave/convex patterns 40 (the data track patterns 40 t and the servopatterns 40 sb) on the magnetic disk 10B so that the magnetic disk 10Bcan be manufactured by imprinting. In this case, the concave/convexpattern 39 of the stamper 30 is formed so that convex parts 39 acorrespond to the concave parts 40 b (non-recording regions as “one ofthe regions” for the present invention) in the concave/convex patterns40 of the magnetic disk 10B, and concave parts 39 b correspond to theconvex parts 40 a (recording regions as “other of the regions” for thepresent invention) in the concave/convex patterns 40. Note that themethod of manufacturing the magnetic disk 10B by imprinting using astamper is the same as the method of manufacturing the magnetic disk 10Adescribed above, and therefore detailed description thereof is omitted.

As shown in FIG. 18, the burst patterns BP1 b are formed on the magneticdisk 10B so that end regions including end parts in the radial directionof the convex parts 40 a formed in the first burst region Ab1 b and theend regions including end parts in the radial direction of the convexparts 40 a formed in the second burst region Ab2 b, for example, overlapone another in the radial direction at the track centers (the centers ofdata recording tracks in the radial direction). Accordingly, on themagnetic disk 10B, the length L21 along the radial direction of theconvex parts 40 a (burst signal units) formed in the burst regions Ab1b, Ab2 b is longer than the track pitch Tp. As a result, when theposition of the magnetic head 3 relative to the magnetic disk 10Bchanges and the magnetic head 3 (the reproducing element Rb) movesrelative to the magnetic disk 10B in the direction of the arrow A fromthe position P1 to the position P2, for example, the output level of theoutput signal from the magnetic head 3 in the first burst region Ab1 bis shown by the solid line Ab. Also, when the magnetic head 3 movesrelative to the magnetic disk 10B in the direction of the arrow B fromthe position P3 to the position P4, for example, the output level of theoutput signal from the magnetic head 3 in the second burst region Ab2 bis shown by the solid line Bb. In this case, if the output signal shownby the solid line Ab is set as S1 and the output signal shown by thesolid line Bb is set as S2, the PES obtained from the burst pattern BP1b is “(S1−S2)/(S1+S2)”. Accordingly, the PES obtained by the burstpattern BP1 b has the characteristics shown by the solid line in FIG.18.

On the other hand, on the conventional magnetic disk 10 x 1, asdescribed earlier, when the magnetic head (the reproducing element Rx)moves relative to the magnetic disk 10 x 1 in the direction of the arrowA from the position P1 to the position P2, for example, the output levelof the output signal from the magnetic head is shown by the dot-dashline Ax. Also, when the magnetic head moves relative to the magneticdisk 10 x 1 in the direction of the arrow B from the position P3 to theposition P4, for example, the output level of the output signal from themagnetic head is shown by the dot-dash line Bx. As a result, the PESobtained from the servo patterns Ps1, Ps2 on the conventional magneticdisk 10 x 1 has the characteristics shown by the dot-dash line shown inFIG. 18.

In this case, when the magnetic head 3 has moved in the direction of thearrow C from a state where the magnetic head 3 is positioned at theposition P0 (in this example, the track center), with the conventionalmagnetic disk 10 x 1, the range in which the position of the magnetichead can be detected based on the PES is the range from the position P0to the position Pxc. On the other hand, with the magnetic disk 10B, thecontrol unit 6 can detect the position of the magnetic head 3 based onthe PES in a wide range from the position P0 to the position Pbc. Also,when the magnetic head 3 has moved from the position P0 in the directionof the arrow D, with the conventional magnetic disk 10 x 1, the range inwhich the position of the magnetic head can be detected based on the PESis the range from 'the position P0 to the position Pxd. On the otherhand, with the magnetic disk 10B, the control unit 6 can detect theposition of the magnetic head 3 based on the PES in a wide range fromthe position P0 to the position Pbd. Accordingly, with the magnetic disk10B, even when the magnetic head 3 is greatly displaced from the trackcenter, it is possible to detect such displacement based on the PES andmake the magnetic head 3 on-track to a desired track.

On the magnetic disk 10B, as described above, the data track patterns 40t and the servo patterns 40 sb are formed so that the width Wr of themagnetic head 3, the formation pitch (the track pitch Tp) along theradial direction of the convex parts 40 a in the data track pattern 40t, and the length L21 (“BW” for the present invention) along the radialdirection of the convex parts 40 a formed in the first burst region Ab1b to the fourth burst region Ab4 b satisfy the condition“(1−M)·Tp/N+BW≦Wr≦(3·M−1)·Tp/N−BW”. Accordingly, with the magnetic disk10B, the width Wr of the reproducing element Rb can be defined withcomparatively freely without the width Wr of the reproducing element Rbbeing primarily determined by the lengths of the various parts of thedata track patterns 40 t and the servo patterns 40 sb. In other words,unlike the conventional magnetic disk 10 x 1, the lengths of the variousparts of the data track patterns 40 t and the servo patterns 40 sb canbe set without being primarily determined by the width Wr of thereproducing element Rb of the magnetic head 3.

More specifically, as shown in FIG. 19, on the magnetic disk 10B, thelength L22 that is the formation pitch along the radial direction of theconvex parts 40 a formed in the first burst region Ab1 b is double thetrack pitch Tp (i.e., “(M/N)·Tp·2”). In this case, the length L22described above is equal to the length L20 described above (a lengthalong the radial direction of a “predetermined range” for the presentinvention). This means that on the magnetic disk 10B, four (i.e., “2·M”)centers C1 b, C2 b, . . . in the radial direction of the burst patternsBP1 b, BP2 b, . . . are present at intervals of half the track pitch Tp((1/N)·Track Pitch) within a range of the length L22. More specifically,the convex parts 40 a (burst signal units) in the first burst region Ab1b to the fourth burst region Ab4 b are formed so that the centers C1 b,C2 b, . . . of the burst patterns BP1 b, BP2 b, . . . are present nearboth ends of the convex parts 40 a in the radial direction. Accordingly,in the first burst region Ab1 b, for example, the centers C1 b in theradial direction of two burst patterns BP1 b are present in the range ofthe length L22 described above that is the formation pitch along theradial direction of the convex parts 40 a. Also, the centers C1 b, C2 bin the radial direction of two sets (M sets) of burst patterns BP1 b,BP2 b, that is, four (2·M) centers C1 b, C2 b, . . . are present in therange of the length L22.

Accordingly, on the magnetic disk 10B, a length L26 along the radialdirection of the range in which tracking servo control is to beperformed for the magnetic head 3 based on the PES obtained from oneburst pattern BP1 b, for example, is one quarter (1/(2·M)) of the lengthL22 described above. In this case, the length L26 is the half the trackpitch Tp (i.e., (M/N)·Tp·2/(2·M)=(1/N)·Tp), and on the magnetic disk10B, half the track pitch Tp is the length L26 that is equal to thewidth of the data recording tracks and the width of the inter-trackconcave parts. That is, on the magnetic disk 10B, the range for whichtracking servo control is to be carried out for the magnetic head 3based on the PES obtained from the burst pattern BP1 b is within therange of the length L26 that is equal to the width of the data recordingtracks and the width of the inter-track concave parts. Also, the lengthL24 that is the amount by which the end regions including the end partsof the convex parts 40 a formed in the first burst region Ab1 b and theend regions including the end parts of the convex parts 40 a formed inthe second burst region Ab2 b overlap in the radial direction is alength (BW−(M/N)·Tp) produced by subtracting half the length L22 fromthe length L21 of the convex parts 40 a, and is equal to a lengthproduced by subtracting the track pitch Tp from the length L21.

Here, in a state where the reproducing element Rb is located at theposition P5 that is one end part of the range (length L26) for whichtracking servo control is to be carried out (i.e., in a state where thecenter in the width direction of the reproducing element Rb is above theposition P5), if the width Wr of the reproducing element Rb is narrowerthan the width Wr1 b in FIG. 19, a gap is produced in the radialdirection (the direction of tracking servo control) between the endparts of the reproducing element Rb and the end parts of the convexparts 40 a formed in the first burst region Ab1 b. Since this gap is adead zone, the width Wr of the reproducing element Rb needs to be equalto or greater than the width Wr1 b shown in FIG. 19. As shown in FIG.19, the width Wr1 b is double the total of the length L24 a and thelength L26 a. Here, the length L24 a is half of the length L24 and thelength L26 a is half of the length L26 (i.e., Tp/(2·N)). That is, halfthe width Wr1 b is a length (1−M)·Tp/(2·N)+BW/2 produced by subtracting¼ of the track pitch Tp from the total of (i) half the length (thelength L24 described above) produced by subtracting the track pitch Tpfrom the length L21 (i.e., the length L24 a: BW/2−(M/N)·Tp/2) and (ii)half of half the track pitch Tp (the length L26 described above) (thelength L26 a: Tp/(2·N)), or in other words, by subtracting ¼ of thetrack pitch Tp from half the length L21. Accordingly, the width Wr1 b isa length produced by subtracting “(M−1)·Tp/N”, which is half the trackpitch Tp, from the length L21 (BW), which matches the “(1−M)·Tp/N+BW”term in the condition of the present invention.

On the other hand, in a state where the reproducing element Rb islocated at the position P6 that is another end part of the range forwhich tracking servo control is to be carried out (the length L26)(i.e., in a state where the center of the reproducing element Rb in thewidth direction is above the position P6), if the width Wr of thereproducing element Rb is wider than the width Wr2 b shown in FIG. 19,the end part of the reproducing element Rb protrudes in the radialdirection (the direction in which tracking servo control is carried out)onto an adjacent convex part 40 a formed in the first burst region Ab1b. Since the protruding amount is a dead zone, the width Wr of thereproducing element Rb needs to be equal to or below the width Wr2 bshown in FIG. 19. The width Wr2 b is double the length produced bysubtracting a length L28 from a length L27 ((M/N)·Tp·2−BW) produced bysubtracting the length L21 from the length L22. Here, the length L28 isproduced by subtracting the length L24 a from half the length L26, thatis, by subtracting the length L24 a (BW/2−(M/N)·Tp/2) from half thelength L26 that itself is half the track pitch Tp (i.e., half the lengthL26=Tp/(2·N)). That is, half the width Wr2 b is the total((3·M−1)·Tp/(2·N)−BW/2) of (i) a length produced by subtracting ¼ of thetrack pitch Tp (i.e., Tp/(2·N)) from the length L27 and (ii) the lengthL24 a. Accordingly, the width Wr2 b is a length produced by subtractingthe length L21 (BW) from ((3·M−1)·Tp/N) that is 5/2 times the trackpitch Tp, which matches the “(3·M−1)·Tp/N−BW” term in the condition forthe present invention.

As described above, the track pitch Tp and the length L26 on themagnetic disk 10B are set so as to satisfy the condition“(1−M)·Tp/N+BW≦Wr≦(3·M−1)·Tp/N−BW”. Accordingly, for reproducingelements Rb of various widths Wr in a range from the width Wr1 b to thewidth Wr2 b set as described above, with the magnetic disk 10B, theposition of the magnetic head 3 (the reproducing element Rb) above themagnetic disk 10B can be specified without producing dead zones. Here,with the magnetic disk 10B, the burst patterns BP1 b, BP2 b, are formedin the burst pattern regions Abb so that the interval along the radialdirection between the centers C1 b, C2 b, . . . in the radial directionof the burst patterns BP1 b, BP2 b . . . is (½)·track pitch Tp (anexample where N=2 for (1/N·track pitch)). Accordingly, in the same wayas with the magnetic disk 10A described above, even if the width Wr ofthe reproducing element Rb is narrower than the track pitch Tp, it willbe possible to specify the position of the magnetic head 3 (thereproducing element Rb) above the magnetic disk 10B without a dead zonebeing produced. This means that by using a reproducing element Rb whosewidth Wr is narrower than the track pitch Tp as necessary, it ispossible to avoid “side reading”.

Also, with the magnetic disk 10B, the formation pitch in the radialdirection of the burst patterns BP1 b, BP2 b, . . . is set at (½)·thetrack pitch Tp (an example where N, which is a natural number of two orhigher, is 2 for the term “(1/N)·Track Pitch”). Accordingly, in the sameway as with the magnetic disk 10A described above, a process thatpositions the reproducing element Rb at a track center based on thevalue of the PES can be carried out easily. Also, by having the centersC1 b along the radial direction of the burst patterns BP1 b match thetrack centers, it is possible to specify that the reproducing element Rbis positioned at a track center when the value of the PES is “0”. Bydoing so, as with the magnetic disk 10A, it is possible to easilyposition the reproducing element Rb on a track center without a complexprocess being necessary.

In this way, according to the magnetic disk 10B and the hard disk drive1, by forming the burst signal units so that M sets (in the aboveexample, two sets) of burst patterns BP1 b, BP2 b, . . . with two typesof burst signal units constructed of convex parts 40 a (recordingregions) are formed and so that in at least one part (as one example,the entire region) out of the regions from the inner periphery region tothe outer periphery region, end regions including facing end parts inthe radial direction of the convex parts 40 a formed in the first burstregion Ab1 b and the second burst region Ab2 b overlap in the radialdirection and end regions including facing end parts in the radialdirection of the convex parts 40 a formed in the third burst region Ab3b and the fourth burst region Ab4 b overlap in the radial direction, itis possible to sufficiently widen the detectable zone for detecting theposition of the magnetic head 3 (the reproducing element Rb) based onthe PES, and as a result, even if there is variation in the outputsignal outputted from the magnetic head 3 corresponding to the burstpatterns BP1 b, BP2 b, . . . due to noise or the like, it will still bepossible to reliably detect positional displacements of the magnetichead 3 and to carry out proper tracking servo control. Also, unlike theconventional magnetic disk 10 x 1 where there is only one set of burstpatterns (i.e., where M=1), there is no need for the width Wr of thereproducing element Rb of the magnetic head 3 to match the track pitchTp, and therefore the data track patterns 40 t and the servo patterns 40sb can be designed with increased freedom. Also, unlike the conventionalmagnetic disk 10 x 2 where there are two (M=2) sets of burst patternsbut the centers in the radial direction of the burst patterns aredisposed at intervals equal to the track pitch, the width Wr of thereproducing element Rb does not need to be wider than the track pitchTp, and therefore it is possible to sufficiently suppress “sidereading”.

According to the hard disk drive 1 equipped with the magnetic disk 10B,by forming the burst patterns BP1 b, BP2 b of the magnetic disk 10B sothat the condition to be satisfied by the magnetic recording mediumaccording to the present invention “(1−M)·Tp/N+BW≦Wr≦(3·M−1)·Tp/N−BW” issatisfied, by using a magnetic head 3 with a reproducing element Rb witha width Wr that satisfies the above condition, it is possible tosufficiently widen the detectable zone for detecting the position of themagnetic head 3 (the reproducing element Rb) based on the PES withoutproducing dead zones for the burst patterns, which makes it possible tocarry out proper tracking servo control. Here, unlike the conventionalmagnetic disk 10 x 1, since the track pitch Tp and the length L21 alongthe radial direction of the burst signal units (the convex parts 40 a)are not primarily determined by the width of the reproducing element Rb,the data track patterns and the servo patterns can be designed withincreased freedom. By doing so, it is possible to suitably change thetrack pitch Tp and the length L21 along the radial direction of theburst signal units (the convex parts 40 a) in accordance with objectssuch as increasing the track density and avoiding side reading. Also,unlike the conventional magnetic disk 10 x 2, the width Wr of thereproducing element Rb does not need to be made wider than the trackpitch Tp, and therefore side reading can be sufficiently avoided. Bydoing so, it is possible to provide a hard disk drive 1 equipped with amagnetic disk 10B capable of high-density recording and not susceptibleto reproduction errors.

In addition, according to the stamper 30 described above, by providing aconcave/convex pattern 39 including convex parts 39 a formedcorresponding to the concave parts 40 b (non-recording regions) of theconcave/convex pattern 40 of the magnetic disk 10B and concave parts 39b formed corresponding to the convex parts 40 a (recording regions) ofthe concave/convex pattern 40 of the magnetic disk 10B, it is possibleto easily manufacture, using a method such as imprinting, a magneticdisk 10B with burst patterns BP1 b, BP2 b, . . . where the detectablezone for detecting the position of the magnetic head 3 based on the PESis sufficiently wide.

Note that the present invention is not limited to the constructionsdescribed above. For example, although two sets of burst patterns BP1 a,BP2 a are formed on the magnetic disk 10A and two sets of burst patternsBP1 b, BP2 b are formed on the magnetic disk 10B as the M sets of burstpatterns for the present invention, the value of “M” is not limited totwo and may be three or higher. In the same way, the value of “N” in theterm “(1/N)·Track Pitch” that sets the distance between the centers inthe radial direction (i.e., the intervals at which the centers arepresent) of the burst patterns according to the present invention is notlimited to two as with the magnetic disks 10A, 10B described above, andany natural number of three or higher can be selected. In addition, withthe magnetic disks 10A, 10B described above, although the burst patternsare formed so that one type of burst signal units and the other type ofburst signal units for the present invention are separated from oneanother in the direction of rotation, such burst signal units do notneed to be separated in the direction of rotation, and the burstpatterns can be formed so that the burst signal units touch in thedirection of rotation (another example of where the burst signal unitsare formed so that the burst signal units “do not overlap in thedirection of rotation”).

In addition, on the magnetic disks 10A, 10B described above, althoughthe entire convex parts 40 a in the concave/convex patterns 40 from theprotruding end parts (the surfaces of the magnetic disks 10A, 10B) tothe base end parts thereof are formed of the magnetic layer 14 (magneticmaterial), the construction of the “recording regions” and the“non-recording regions” that construct the “pattern” for the presentinvention are not limited to this. More specifically, like a magneticdisk 10C shown in FIG. 20, for example, by forming a thin magnetic layer14 so as to cover concave/convex patterns formed in the glass substrate11 (concave/convex patterns where the concaves and convexes have thesame positional relationship as the concave/convex patterns 40), it ispossible to construct a concave/convex pattern 40 that corresponds tothe “pattern” for the present invention from a plurality of convex parts40 a (recording regions) whose surfaces are formed of magnetic materialand a plurality of concave parts 40 b (non-recording regions) whose basesurfaces are also formed of the magnetic material. Also, like a magneticdisk 10D shown in FIG. 21, it is possible to construct a concave/convexpattern 40 that corresponds to the “pattern” for the present inventionwhere not only the convex parts 40 a (recording regions) but also thebase parts of the concave parts 40 b (non-recording regions) are formedof the magnetic layer 14. As another example, although not shown, it isalso possible to construct a concave/convex pattern 40 that correspondsto the “pattern” for the present invention so as to include convex parts40 a (recording regions) where only the protruding end parts (thesurface side of the magnetic recording medium: the upper end parts inFIG. 21) of the convex parts 40 a in the concave/convex pattern 40 areformed of the magnetic layer 14 and the base end parts of the convexparts 40 a are formed of a non-magnetic material, a soft magneticmaterial, and the like. In this way, when forming the recording regionsand non-recording regions of the magnetic recording medium according tothe present invention using concave/convex patterns, by forming at leastthe protruding end parts of the convex parts that construct therecording regions from a magnetic material, it is possible tosufficiently increase the ability to store a magnetic signal in areadable manner compared to the non-recording regions.

Also, although the magnetic disks 10A, 10B have been described where theconcave/convex patterns 40 including the convex parts 40 a (recordingregions) and the concave parts 40 b (non-recording regions) are formedby forming a concave/convex pattern 42 using the concave/convex pattern41 formed by imprinting where the concave/convex pattern 39 of thestamper 30 is transferred to the resin layer 18 of the preform 20 andthen etching the magnetic layer 14 with the concave/convex pattern 42 asa mask, the construction and method of manufacturing a magneticrecording medium according to the present invention are not limited tosuch. As one example, although not shown, a magnetic recording mediumcan be constructed by forming, in a layer formed of various materialswhose ability to store a magnetic signal in a readable manner is low orvarious materials (as one example, a non-magnetic material) thateffectively cannot store a magnetic signal, concave/convex patterns(concave/convex patterns where the convex parts are formed ofnon-magnetic material or the like) where the positional relationshipbetween concaves and convexes is reversed compared to the concave/convexpatterns 40 described above, and then filling the concave parts in suchconcave/convex patterns with various materials (as one example, amagnetic material) whose ability to store a magnetic signal in areadable manner is high. On a magnetic recording medium manufacturedaccording to this method of manufacturing, the formation regions of theconvex parts in the concave/convex patterns formed in the layer ofnon-magnetic material or the like (concave/convex patterns where thepositional relationship between concaves and convexes is reversedcompared to the concave/convex patterns 40 of the magnetic disks 10A,10B described above) correspond to “non-recording regions” for thepresent invention and the formation regions of the concave parts(regions filled with magnetic material) in the concave/convex patternscorrespond to “recording regions” for the present invention.

In addition, when the concave/convex patterns are formed in the layer ofnon-magnetic material during the manufacturing of the above magneticrecording medium where magnetic material is used to fill concave partsin concave/convex patterns formed in a layer of non-magnetic material orthe like, by using a stamper (not shown) with a concave/convex patternwhere the positional relationship between the concaves and convexes isreversed compared to the concave/convex pattern 39 of the stamper 30described above, it is possible to form a mask pattern by imprinting.This stamper (a stamper with a concave/convex pattern where thepositional relationship between the concaves and convexes is reversedcompared to the concave/convex pattern 39) is another example of a“stamper for manufacturing a magnetic recording medium” according to thepresent invention, on which convex parts are formed corresponding torecording regions (regions filled with magnetic material) as the “oneregion out of the recording regions and the non-recording regions” forthe present invention and concave parts are formed corresponding tonon-recording regions (formation regions of the convex parts in theconcave/convex pattern formed in the layer of non-magnetic material orthe like) as the “other regions” for the present invention.

In addition, although on the magnetic disks 10A, 10B described above,the data track patterns 40 t are formed in the data recording regions Atby concave/convex patterns 40 with a plurality of concentric or spiralconvex parts 40 a (recording regions), the present invention is notlimited to such and it is possible to apply the present invention to apatterned medium where the recording regions that construct the datarecording tracks in the data track patterns are separated from oneanother by having non-recording regions in between in thecircumferential direction of the magnetic recording medium. It is alsopossible to apply the present invention to a magnetic recording mediumwhere data track patterns are formed by magnetically writing variousrecording data in data recording regions constructed of a continuousmagnetic layer, the servo patterns being formed by a pattern (forexample, the concave/convex patterns 40 described above) includingrecording regions and non-recording regions. In addition, by partiallychanging the magnetic characteristics of a continuous magnetic layer,which is formed on a substrate, by ion irradiation or the like, it ispossible to construct a magnetic recording medium (not shown) where apattern including the recording regions and non-recording regions forthe present invention are formed in a continuous magnetic layer. Also,the magnetic recording medium according to the present invention is notlimited to a magnetic recording medium for perpendicular recording likethe magnetic disks 10A, 10B, and can be applied to a magnetic recordingmedium for longitudinal recording.

1. A magnetic recording medium on which are formed: servo patternsformed in servo pattern regions on at least one surface of a substrateby patterns including recording regions and non-recording regions; anddata track patterns where a plurality of data recording tracks areformed with a predetermined track pitch in data recording regions on theat least one surface, wherein M sets of burst patterns are formed alonga direction of rotation of the substrate in a burst pattern region ineach servo pattern region, where M is a natural number of two or higher,each burst pattern is formed so as to include two types of burst signalunits that are positioned at different distances from a center of thedata track patterns and have an equal length along a radial direction ofthe substrate, the length along the radial direction being (2·M/N) timesthe track pitch, where N is a natural number of two or higher, and sothat in a predetermined range where both ends in the radial direction donot match a center in the radial direction of a burst pattern, (2·M)centers in the radial direction of the burst patterns are present atintervals of (1/N) times the track pitch in the radial direction, andthe two types of burst signal units are constructed by the non-recordingregions so that a first type of burst signal units and a second type ofburst signal units out of the two types of burst signal units do notoverlap in the direction of rotation, centers in the radial direction ofthe burst signal units of a same type are separated in the radialdirection by (2·M/N) times the track pitch, centers in the radialdirection of the first type of burst signal units and centers in theradial direction of the second type of burst signal units are separatedin the radial direction by (M/N) times the track pitch, and in at leastone part out of regions from an inner periphery region to an outerperiphery region of the substrate, end parts positioned close to thesecond type of burst signal units out of both end parts in the radialdirection of the first type of burst signal units and end partspositioned close to the first type of burst signal units out of both endparts in the radial direction of the second type of burst signal unitsare separated in the radial direction via the recording regions.
 2. Amagnetic recording medium on which are formed: servo patterns formed inservo pattern regions on at least one surface of a substrate by patternsincluding recording regions and non-recording regions; and data trackpatterns where a plurality of data recording tracks are formed with apredetermined track pitch in data recording regions on the at least onesurface, wherein M sets of burst patterns are formed along a directionof rotation of the substrate in a burst pattern region in each servopattern region, where M is a natural number of two or higher, each burstpattern is formed so as to include two types of burst signal units thatare positioned at different distances from a center of the data trackpatterns and have an equal length along a radial direction of thesubstrate, the length along the radial direction being (2·M/N) times thetrack pitch, where N is a natural number of two or higher, and so thatin a predetermined range where both ends in the radial direction do notmatch a center in the radial direction of a burst pattern, (2·M) centersin the radial direction of the burst patterns are present at intervalsof (1/N) times the track pitch in the radial direction, and the twotypes of burst signal units are constructed by the recording regions sothat a first type of burst signal units and a second type of burstsignal units out of the two types of burst signal units do not overlapin the direction of rotation, centers in the radial direction of theburst signal units of a same type are separated in the radial directionby (2·M/N) times the track pitch, centers in the radial direction of thefirst type of burst signal units and centers in the radial direction ofthe second type of burst signal units are separated in the radialdirection by (M/N) times the track pitch, and in at least one part outof regions from an inner periphery region to an outer periphery regionof the substrate, end regions including end parts positioned close tothe second type of burst signal units out of both end parts in theradial direction of the first type of burst signal units and end regionsincluding end parts positioned close to the first type of burst signalunits out of both end parts in the radial direction of the second typeof burst signal units overlap in the radial direction.
 3. Arecording/reproducing apparatus comprising: a magnetic recording mediumaccording to claim 1; a magnetic head that reads a control signal usedfor tracking servo control from the servo pattern regions of themagnetic recording medium; and a control unit that carries out thetracking servo control based on the control signal read via the magnetichead, wherein the burst patterns are formed on the magnetic recordingmedium so as to satisfy a condition(M+1)·Tp/N−BW≦Wr≦(M−1)·Tp/N+BW where Wr is a reproducing head width ofthe magnetic head, BW is a length along the radial direction of theburst signal units, and Tp is the track pitch.
 4. Arecording/reproducing apparatus comprising: a magnetic recording mediumaccording to claim 2; a magnetic head that reads a control signal usedfor tracking servo control from the servo pattern regions of themagnetic recording medium; and a control unit that carries out thetracking servo control based on the control signal read via the magnetichead, wherein the burst patterns are formed on the magnetic recordingmedium so as to satisfy a condition(1−M)·Tp/N+BW≦Wr≦(3·M−1)·Tp/N−BW where Wr is a reproducing head width ofthe magnetic head, BW is a length along the radial direction of theburst signal units, and Tp is the track pitch.
 5. A stamper formanufacturing a magnetic recording medium, the stamper having aconcave/convex pattern including convex parts formed corresponding toone region out of the recording regions and the non-recording regions ofthe patterns on the magnetic recording medium according to claim 1, andconcave parts formed corresponding to other regions in the patterns onthe magnetic recording medium.
 6. A stamper for manufacturing a magneticrecording medium, the stamper having a concave/convex pattern includingconvex parts formed corresponding to one region out of the recordingregions and the non-recording regions of the patterns on the magneticrecording medium according to claim 2, and concave parts formedcorresponding to other regions in the patterns on the magnetic recordingmedium.